diff --git a/cmd/generate-std-packages/main.go b/cmd/generate-std-packages/main.go
index 43a28154..3c9edc18 100644
--- a/cmd/generate-std-packages/main.go
+++ b/cmd/generate-std-packages/main.go
@@ -1,7 +1,6 @@
 package main
 
 import (
-	"bytes"
 	"fmt"
 	"go/importer"
 	"go/types"
@@ -9,56 +8,32 @@ import (
 	"log"
 	"reflect"
 	"strings"
-	"text/template"
 )
 
-func parseTmpl(tmpl string, data map[string]interface{}) ([]byte, error) {
-	parsedTmpl, err := template.New("tmpl").Parse(tmpl)
-	if err != nil {
-		return nil, err
-	}
-
-	var result bytes.Buffer
-	if err := parsedTmpl.Execute(&result, data); err != nil {
-		return nil, err
-	}
-
-	return result.Bytes(), nil
+type pkgFuncType struct {
+	PkgName      string `json:"pkg_name"`
+	FuncTypeName string `json:"func_type_name"`
+	Expr         string `json:"expr"`
 }
 
-func generatePackageImportCode18(pkgImportName string) ([]byte, error) {
-	var pkgTmpl = `package packages
-
-import (
-	{{.import_packages}}
-)
-
-{{.extra}}
-
-func init() {
-	{{.package_no_struct_types}}
-	Packages["{{.name}}"] = map[string]interface{}{
-{{.package_funcs}}
-	}
-	PackageTypes["{{.name}}"] = map[string]interface{}{
-{{.package_types}}
-	}
-{{.import_multi_version_call}}
-}
-`
+func dealPackageScope(pkgImportName string, goVersion version) ([]pkgFuncType, []pkgFuncType, []string) {
 	pkg, err := importer.Default().Import(pkgImportName)
 	if err != nil {
-		return nil, err
+		log.Fatal(err)
 	}
 
-	var scope = pkg.Scope()
-	var funcOrVars []string
-	var typs []string
+	var notTypes []pkgFuncType
+	var typeAssigns []pkgFuncType
 	var typeVars []string
-	var importPackages []string
+	var scope = pkg.Scope()
 
 	for _, name := range scope.Names() {
-		if include(pkgImportName, name, black) || include(pkgImportName, name, in19) || include(pkgImportName, name, in110) {
+		if include(pkgImportName, name, black) {
+			continue
+		}
+		if goVersion.isGeneral() && (include(pkgImportName, name, in19) || include(pkgImportName, name, in110)) {
+			continue
+		} else if (goVersion.is19() && !include(pkgImportName, name, in19)) || (goVersion.is110() && !include(pkgImportName, name, in110)) {
 			continue
 		}
 
@@ -71,179 +46,93 @@ func init() {
 					varName = varName + "_"
 				}
 				typeVars = append(typeVars, fmt.Sprintf(`        var %s %s.%s`, varName, getpackageTailName(pkgImportName), name))
-				typs = append(typs, fmt.Sprintf(`        "%s": reflect.TypeOf(&%s).Elem(),`, name, varName))
+				typeAssigns = append(typeAssigns, pkgFuncType{pkgImportName, name, fmt.Sprintf(`reflect.TypeOf(&%s).Elem()`, varName)})
 			default:
-				funcOrVars = append(funcOrVars, fmt.Sprintf(`        "%s": %s.%s,`, name, getpackageTailName(pkgImportName), name))
+				notTypes = append(notTypes, pkgFuncType{pkgImportName, name, getConvertedName(pkgImportName, name)})
 			}
 		}
 	}
 
+	return notTypes, typeAssigns, typeVars
+}
+
+func dealExtra(pkgImportName string, goVersion version) (string, []pkgFuncType, []pkgFuncType) {
 	var extraDetail string
+	var notTypes []pkgFuncType
+	var typeAssigns []pkgFuncType
+
 	if extra, ok := extraList[pkgImportName]; ok {
-		extraDetail = extra.detail
-		if extra.packageImport != nil {
-			for _, v := range extra.packageImport {
-				funcOrVars = append(funcOrVars, fmt.Sprintf(`        "%s": "%s",`, v.k, v.v))
+		if goVersion.isGeneral() {
+			extraDetail = extra.detail
+			if extra.packageImport != nil {
+				for _, v := range extra.packageImport {
+					notTypes = append(notTypes, pkgFuncType{pkgImportName, v.k, v.v})
+				}
+			}
+			if extra.packageTypesImport != nil {
+				for _, v := range extra.packageTypesImport {
+					typeAssigns = append(typeAssigns, pkgFuncType{pkgImportName, v.k, v.v})
+				}
 			}
 		}
-		if extra.packageTypesImport != nil {
-			for _, v := range extra.packageTypesImport {
-				typs = append(typs, fmt.Sprintf(`        "%s": %s,`, v.k, v.v))
+		if goVersion.is18() {
+			extraDetail = extra.detail
+			if extra.packageImport != nil {
+				for _, v := range extra.packageImport {
+					notTypes = append(notTypes, pkgFuncType{pkgImportName, v.k, v.v})
+				}
+			}
+			if extra.packageTypesImport != nil {
+				for _, v := range extra.packageTypesImport {
+					typeAssigns = append(typeAssigns, pkgFuncType{pkgImportName, v.k, v.v})
+				}
 			}
 		}
-	} else {
-		pkgTmpl = strings.Replace(pkgTmpl, "{{.extra}}", "", -1)
+
 	}
 
-	importPackages = append(importPackages, fmt.Sprintf(`"%s"`, pkgImportName))
+	return extraDetail, notTypes, typeAssigns
+}
+
+func generatePackageImportCodeAll(pkgImportName string, goVersion version) ([]byte, error) {
+	notTypes, typeAssigns, typeVars := dealPackageScope(pkgImportName, goVersion)
+	extraDetail, notTypes2, typeAssigns2 := dealExtra(pkgImportName, goVersion)
+
+	notTypes = append(notTypes, notTypes2...)
+	typeAssigns = append(typeAssigns, typeAssigns2...)
+
+	var importPackages = []string{fmt.Sprintf(`"%s"`, pkgImportName)}
 	if len(typeVars) > 0 {
 		importPackages = append(importPackages, `"reflect"`)
-	} else {
-		pkgTmpl = strings.Replace(pkgTmpl, "{{.package_no_struct_types}}\n", "", -1)
-	}
-
-	if len(typs) == 0 {
-		pkgTmpl = strings.Replace(pkgTmpl, "\n	PackageTypes[\"{{.name}}\"] = map[string]interface{}{\n{{.package_type}}\n	}", "", -1)
 	}
 
 	var importMultiVersionCall string
-	if v, ok := ruleList[pkgImportName]; ok && (v.in19 != nil || v.in110 != nil) {
+	if v, ok := ruleList[pkgImportName]; ok && goVersion.isGeneral() && (v.in19 != nil || v.in110 != nil) {
 		importMultiVersionCall += getPackageInitName(pkgImportName) + "()\n"
-		build := "// +build go1.8"
-		if v.in19 != nil {
-			build += ",!go1.9,!go1.10"
-		} else if v.in110 != nil {
-			build += ",!go1.10"
-		}
-		if err = ioutil.WriteFile(go18.filename(pkgImportName), []byte(build+"\n\npackage packages\n\nfunc "+getPackageInitName(pkgImportName)+"() { }\n"), 0644); err != nil {
-			log.Fatal(err)
-		}
-	} else {
-		pkgTmpl = strings.Replace(pkgTmpl, "{{.import_multi_version_call}}", "", -1)
+	}
+
+	var pkgTmpl = pkgExtraTmpl
+	if goVersion == gogo {
+		pkgTmpl = pkgNormalTmpl
 	}
 
 	return parseTmpl(pkgTmpl, map[string]interface{}{
+		"build_tag":                 goVersion.buildTag(),
 		"name":                      pkgImportName,
-		"package_funcs":             strings.Join(funcOrVars, "\n"),
-		"package_types":             strings.Join(typs, "\n"),
+		"package_funcs":             notTypes,
+		"package_types":             typeAssigns,
 		"package_no_struct_types":   strings.Join(typeVars, "\n"),
 		"import_packages":           strings.Join(importPackages, "\n"),
 		"extra":                     extraDetail,
+		"import_func_name":          getPackageInitName(pkgImportName),
 		"import_multi_version_call": importMultiVersionCall,
 	})
 }
 
-func generatePackageImportCode18Plus(pkgImportName string, goVersion version) ([]byte, error) {
-	var pkgTmpl = `
-{{.build_tag}}
-
-package packages
-
-import (
-	{{.import_packages}}
-)
-
-{{.extra}}
-
-func {{.import_func_name}}() {
-	{{.package_no_struct_types}}
-{{range $index, $element := .package_funcs}}
-Packages["{{.PkgName}}"]["{{.FuncTypeName}}"] = {{.Expr}}
-{{end}}
-{{range $index, $element := .package_types}}
-PackageTypes["{{.PkgName}}"]["{{.FuncTypeName}}"] = {{.Expr}}
-{{end}}
-}
-`
-
-	type pkgFuncType struct {
-		PkgName      string `json:"pkg_name"`
-		FuncTypeName string `json:"func_type_name"`
-		Expr         string `json:"expr"`
-	}
-	pkg, err := importer.Default().Import(pkgImportName)
-	if err != nil {
-		return nil, err
-	}
-
-	var scope = pkg.Scope()
-	var funcOrVars []pkgFuncType
-	var typs []pkgFuncType
-	var typeVars []string
-	var importPackages []string
-
-	for _, name := range scope.Names() {
-		if include(pkgImportName, name, black) {
-			continue
-		} else if goVersion.is18plus() && !include(pkgImportName, name, in19) {
-			continue
-		} else if goVersion.is110() && !include(pkgImportName, name, in110) {
-			continue
-		}
-
-		sc := scope.Lookup(name)
-		if sc.Exported() {
-			switch reflect.TypeOf(sc) {
-			case reflect.TypeOf(new(types.TypeName)):
-				varName := strings.ToLower(name)
-				if keyword[varName] {
-					varName = varName + "_"
-				}
-				typeVars = append(typeVars, fmt.Sprintf(`        var %s %s.%s`, varName, getpackageTailName(pkgImportName), name))
-				typs = append(typs, pkgFuncType{pkgImportName, name, fmt.Sprintf(`reflect.TypeOf(&%s).Elem()`, varName)})
-			default:
-				funcOrVars = append(funcOrVars, pkgFuncType{pkgImportName, name, getpackageTailName(pkgImportName) + "." + name})
-			}
-		}
-	}
-
-	var extraDetail string
-	if extra, ok := extraList[pkgImportName]; goVersion.is18() && ok {
-		extraDetail = extra.detail
-		if extra.packageImport != nil {
-			for _, v := range extra.packageImport {
-				funcOrVars = append(funcOrVars, pkgFuncType{pkgImportName, v.k, v.v})
-			}
-		}
-		if extra.packageTypesImport != nil {
-			for _, v := range extra.packageTypesImport {
-				typs = append(typs, pkgFuncType{pkgImportName, v.k, v.v})
-			}
-		}
-	} else {
-		pkgTmpl = strings.Replace(pkgTmpl, "{{.extra}}", "", -1)
-	}
-
-	importPackages = append(importPackages, fmt.Sprintf(`"%s"`, pkgImportName))
-	if len(typeVars) > 0 {
-		importPackages = append(importPackages, `"reflect"`)
-	} else {
-		pkgTmpl = strings.Replace(pkgTmpl, "{{.package_no_struct_types}}\n", "", -1)
-	}
-
-	return parseTmpl(pkgTmpl, map[string]interface{}{
-		"build_tag":               goVersion.buildTag(),
-		"name":                    pkgImportName,
-		"package_funcs":           funcOrVars,
-		"package_types":           typs,
-		"package_no_struct_types": strings.Join(typeVars, "\n"),
-		"import_packages":         strings.Join(importPackages, "\n"),
-		"extra":                   extraDetail,
-		"import_func_name":        getPackageInitName(pkgImportName),
-	})
-}
-
 func runOneVersion(pkgImportName string, goVersion version) {
-	var result []byte
-	var err error
-	if goVersion == gogo {
-		if result, err = generatePackageImportCode18(pkgImportName); err != nil {
-			log.Fatal(err)
-		}
-	} else {
-		if result, err = generatePackageImportCode18Plus(pkgImportName, goVersion); err != nil {
-			log.Fatal(err)
-		}
+	result, err := generatePackageImportCodeAll(pkgImportName, goVersion)
+	if err != nil {
+		log.Fatal(err)
 	}
 
 	if err = ioutil.WriteFile(goVersion.filename(pkgImportName), result, 0644); err != nil {
@@ -253,15 +142,25 @@ func runOneVersion(pkgImportName string, goVersion version) {
 
 func run(pkgImportName string) {
 	if v, ok := ruleList[pkgImportName]; ok {
+		build := "// +build "
+
 		if v.in19 != nil {
-			runOneVersion(pkgImportName, go18plus)
+			build += "!go1.9"
+			runOneVersion(pkgImportName, go19) // generate pkg.19.go
 		}
 		if v.in110 != nil {
-			runOneVersion(pkgImportName, go110)
+			build += "!go1.10"
+			runOneVersion(pkgImportName, go110) // generate pkg.110.go
+		}
+		if build != "// +build " {
+			// generate pkg.18.go
+			if err := ioutil.WriteFile(go18.filename(pkgImportName), []byte(build+"\n\npackage packages\n\nfunc "+getPackageInitName(pkgImportName)+"() { }\n"), 0644); err != nil {
+				log.Fatal(err)
+			}
 		}
 	}
 
-	runOneVersion(pkgImportName, gogo)
+	runOneVersion(pkgImportName, gogo) // generate pkg.go and
 }
 
 func main() {
diff --git a/cmd/generate-std-packages/rule.go b/cmd/generate-std-packages/rule.go
index efaa5cbe..b1467a8c 100644
--- a/cmd/generate-std-packages/rule.go
+++ b/cmd/generate-std-packages/rule.go
@@ -18,10 +18,13 @@ var keyword = map[string]bool{
 	"int":       true,
 }
 
+type convertFunc func(string) string
+
 type rule struct {
-	in19  []string // not in 18
-	in110 []string // not in 18 and 19
-	black []string
+	in19    []string // not in 18
+	in110   []string // not in 18 and 19
+	black   []string
+	convert map[string]convertFunc
 }
 
 var ruleList = map[string]rule{
@@ -30,7 +33,9 @@ var ruleList = map[string]rule{
 	},
 	"math": {
 		in110: []string{"Erfcinv", "Erfinv", "Round", "RoundToEven"},
-		black: []string{"MaxUint64"},
+		convert: map[string]convertFunc{"MaxUint64": func(s string) string {
+			return "uint64(math.MaxUint64)"
+		}},
 	},
 	"math/rand": {
 		in110: []string{"Shuffle"},
@@ -78,3 +83,21 @@ func include(packageName, item, typ string) bool {
 
 	return false
 }
+
+func getConvertedName(pkgImportName, name string) string {
+	n := getpackageTailName(pkgImportName) + "." + name
+
+	rule, ok := ruleList[pkgImportName]
+	if !ok {
+		return n
+	} else if rule.convert == nil {
+		return n
+	}
+
+	f, ok := rule.convert[name]
+	if !ok {
+		return n
+	}
+
+	return f(name)
+}
diff --git a/cmd/generate-std-packages/tmpl.go b/cmd/generate-std-packages/tmpl.go
new file mode 100644
index 00000000..6996d1dd
--- /dev/null
+++ b/cmd/generate-std-packages/tmpl.go
@@ -0,0 +1,114 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"text/template"
+)
+
+var (
+	pkgNormalTmpl = `package packages
+
+import (
+	{{.import_packages}}
+)
+
+{{.extra}}
+
+func init() {
+	{{.package_no_struct_types}}
+
+{{if hasPkgFuncTypeField . "package_funcs"}}
+	Packages["{{.name}}"] = map[string]interface{}{
+		{{range $index, $element := .package_funcs}}
+			"{{.FuncTypeName}}" : {{.Expr}},
+		{{end}}
+	}
+{{end}}
+
+{{if hasPkgFuncTypeField . "package_types"}}
+	PackageTypes["{{.name}}"] = map[string]interface{}{
+		{{range $index, $element := .package_types}}
+			"{{.FuncTypeName}}" : {{.Expr}},
+		{{end}}
+	}
+{{end}}
+
+{{.import_multi_version_call}}
+
+}
+`
+
+	pkgExtraTmpl = `
+{{.build_tag}}
+
+package packages
+
+import (
+	{{.import_packages}}
+)
+
+{{.extra}}
+
+func {{.import_func_name}}() {
+	{{.package_no_struct_types}}
+
+	{{range $index, $element := .package_funcs}}
+		Packages["{{.PkgName}}"]["{{.FuncTypeName}}"] = {{.Expr}}
+	{{end}}
+
+	{{range $index, $element := .package_types}}
+		PackageTypes["{{.PkgName}}"]["{{.FuncTypeName}}"] = {{.Expr}}
+	{{end}}
+}
+`
+)
+
+func hasPkgFuncTypeField(v interface{}, name string) bool {
+	m, ok := v.(map[string]interface{})
+	if !ok {
+		return false
+	}
+
+	n, ok := m[name]
+	if !ok {
+		return false
+	}
+
+	p, ok := n.([]pkgFuncType)
+
+	return ok && len(p) > 0
+}
+
+func parseTmpl(tmpl string, data map[string]interface{}) ([]byte, error) {
+	for k, v := range data {
+		if v == "" {
+			tmpl = strings.Replace(tmpl, "{{."+k+"}}", "", -1)
+		}
+	}
+
+	parsedTmpl, err := template.New("tmpl").Funcs(template.FuncMap{"hasPkgFuncTypeField": hasPkgFuncTypeField}).Parse(tmpl)
+	if err != nil {
+		return nil, err
+	}
+
+	var result bytes.Buffer
+	if err := parsedTmpl.Execute(&result, data); err != nil {
+		return nil, err
+	}
+
+	s := strings.Split(result.String(), "\n")
+	var s2 []string
+	for i := 0; i < len(s); i++ {
+		if s3 := strings.TrimSpace(s[i]); s3 == "" {
+			continue
+		}
+
+		s2 = append(s2, s[i])
+		if strings.HasPrefix(s[i], "// +build") {
+			s2 = append(s2, "\n")
+		}
+	}
+
+	return []byte(strings.Join(s2, "\n")), nil
+}
diff --git a/cmd/generate-std-packages/version.go b/cmd/generate-std-packages/version.go
index b2e945ce..af43c887 100644
--- a/cmd/generate-std-packages/version.go
+++ b/cmd/generate-std-packages/version.go
@@ -7,32 +7,41 @@ import (
 type version string
 
 const (
-	gogo     version = "general"
-	go18     version = "1.8"
-	go18plus version = "1.9 1.10"
-	go110    version = "1.10"
+	gogo  version = "general"
+	go18  version = "1.8"  // from Go version 1.8 onward
+	go19  version = "1.9"  // from Go version 1.9 onward
+	go110 version = "1.10" // from Go version 1.10 onward
 )
 
-func (v version) is18() bool {
-	return v == go18
+func (v version) is19() bool {
+	return v == go19
 }
 
-func (v version) is18plus() bool {
-	return v == go18plus
+func (v version) is18() bool {
+	return v == go18
 }
 
 func (v version) is110() bool {
 	return v == go110
 }
 
+func (v version) isGeneral() bool {
+	return v == gogo
+}
+
 func (v version) buildTag() string {
 	switch v {
-	case go18:
-		return "// +build go1.8"
-	case go18plus:
-		return "// +build go1.9 go1.10"
-	case go110:
-		return "// +build go1.10"
+	case go18, go19, go110:
+		return "// +build go" + string(v)
+	}
+
+	return ""
+}
+
+func (v version) buildOppositeTag() string {
+	switch v {
+	case go18, go19, go110:
+		return "// +build !go" + string(v)
 	}
 
 	return ""
@@ -40,17 +49,15 @@ func (v version) buildTag() string {
 
 // filename encoding/json return encoding.json.19.110.go
 func (v version) filename(packageImportName string) string {
-	name := strings.Join(strings.Split(packageImportName, "/"), ".")
+	pkgName := strings.Join(strings.Split(packageImportName, "/"), ".")
+	versionName := strings.Replace(string(v), ".", "", -1)
+
 	switch v {
-	case go18:
-		return "./packages/" + name + ".18.go"
-	case go18plus:
-		return "./packages/" + name + ".19.110.go"
-	case go110:
-		return "./packages/" + name + ".110.go"
+	case go18, go19, go110:
+		return "./packages/" + pkgName + "." + versionName + ".go"
 	}
 
-	return "./packages/" + name + ".go"
+	return "./packages/" + pkgName + ".go"
 }
 
 func getpackageTailName(packageImportName string) string {
diff --git a/packages/bytes.go b/packages/bytes.go
index 754e9df4..98ed06c0 100644
--- a/packages/bytes.go
+++ b/packages/bytes.go
@@ -64,5 +64,4 @@ func init() {
 		"Buffer": reflect.TypeOf(&buffer).Elem(),
 		"Reader": reflect.TypeOf(&reader).Elem(),
 	}
-
 }
diff --git a/packages/encoding.json.18.go b/packages/encoding.json.18.go
index 8aa8549d..9fdb3888 100644
--- a/packages/encoding.json.18.go
+++ b/packages/encoding.json.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.9,!go1.10
+// +build !go1.9
 
 package packages
 
diff --git a/packages/encoding.json.19.110.go b/packages/encoding.json.19.go
similarity index 83%
rename from packages/encoding.json.19.110.go
rename to packages/encoding.json.19.go
index 372dbb92..b9b256ea 100644
--- a/packages/encoding.json.19.110.go
+++ b/packages/encoding.json.19.go
@@ -1,4 +1,4 @@
-// +build go1.9 go1.10
+// +build go1.9
 
 package packages
 
@@ -7,7 +7,5 @@ import (
 )
 
 func init_encoding_json() {
-
 	Packages["encoding/json"]["Valid"] = json.Valid
-
 }
diff --git a/packages/encoding.json.go b/packages/encoding.json.go
index cadbd807..a0782dcc 100644
--- a/packages/encoding.json.go
+++ b/packages/encoding.json.go
@@ -51,5 +51,4 @@ func init() {
 		"UnsupportedValueError": reflect.TypeOf(&unsupportedvalueerror).Elem(),
 	}
 	init_encoding_json()
-
 }
diff --git a/packages/errors.go b/packages/errors.go
index 984b6153..8ac16ee2 100644
--- a/packages/errors.go
+++ b/packages/errors.go
@@ -8,6 +8,4 @@ func init() {
 	Packages["errors"] = map[string]interface{}{
 		"New": errors.New,
 	}
-	PackageTypes["errors"] = map[string]interface{}{}
-
 }
diff --git a/packages/flag.go b/packages/flag.go
index 833d2d97..bad3df17 100644
--- a/packages/flag.go
+++ b/packages/flag.go
@@ -56,5 +56,4 @@ func init() {
 		"Getter":        reflect.TypeOf(&getter).Elem(),
 		"Value":         reflect.TypeOf(&value).Elem(),
 	}
-
 }
diff --git a/packages/fmt.go b/packages/fmt.go
index ec26a40c..82c9ee57 100644
--- a/packages/fmt.go
+++ b/packages/fmt.go
@@ -41,5 +41,4 @@ func init() {
 		"State":      reflect.TypeOf(&state).Elem(),
 		"Stringer":   reflect.TypeOf(&stringer).Elem(),
 	}
-
 }
diff --git a/packages/io.go b/packages/io.go
index 332cdb88..a9f90ccf 100644
--- a/packages/io.go
+++ b/packages/io.go
@@ -79,5 +79,4 @@ func init() {
 		"WriterAt":        reflect.TypeOf(&writerat).Elem(),
 		"WriterTo":        reflect.TypeOf(&writerto).Elem(),
 	}
-
 }
diff --git a/packages/io.ioutil.go b/packages/io.ioutil.go
index 01e67bec..72a9b0fc 100644
--- a/packages/io.ioutil.go
+++ b/packages/io.ioutil.go
@@ -15,6 +15,4 @@ func init() {
 		"TempFile":  ioutil.TempFile,
 		"WriteFile": ioutil.WriteFile,
 	}
-	PackageTypes["io/ioutil"] = map[string]interface{}{}
-
 }
diff --git a/packages/log.go b/packages/log.go
index 16cd99b6..0c8f504d 100644
--- a/packages/log.go
+++ b/packages/log.go
@@ -35,5 +35,4 @@ func init() {
 	PackageTypes["log"] = map[string]interface{}{
 		"Logger": reflect.TypeOf(&logger).Elem(),
 	}
-
 }
diff --git a/packages/math.110.go b/packages/math.110.go
index 6eea0f24..5cea3973 100644
--- a/packages/math.110.go
+++ b/packages/math.110.go
@@ -7,13 +7,8 @@ import (
 )
 
 func init_math() {
-
 	Packages["math"]["Erfcinv"] = math.Erfcinv
-
 	Packages["math"]["Erfinv"] = math.Erfinv
-
 	Packages["math"]["Round"] = math.Round
-
 	Packages["math"]["RoundToEven"] = math.RoundToEven
-
 }
diff --git a/packages/math.18.go b/packages/math.18.go
index a531f4e9..e17b1db2 100644
--- a/packages/math.18.go
+++ b/packages/math.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.10
+// +build !go1.10
 
 package packages
 
diff --git a/packages/math.big.go b/packages/math.big.go
index 5c3afef5..3b0a80fb 100644
--- a/packages/math.big.go
+++ b/packages/math.big.go
@@ -42,5 +42,4 @@ func init() {
 		"RoundingMode": reflect.TypeOf(&roundingmode).Elem(),
 		"Word":         reflect.TypeOf(&word).Elem(),
 	}
-
 }
diff --git a/packages/math.go b/packages/math.go
index 8892ffe4..dbdc0460 100644
--- a/packages/math.go
+++ b/packages/math.go
@@ -61,6 +61,7 @@ func init() {
 		"MaxInt8":         math.MaxInt8,
 		"MaxUint16":       math.MaxUint16,
 		"MaxUint32":       math.MaxUint32,
+		"MaxUint64":       uint64(math.MaxUint64),
 		"MaxUint8":        math.MaxUint8,
 		"Min":             math.Min,
 		"MinInt16":        math.MinInt16,
@@ -95,7 +96,5 @@ func init() {
 		"Y1":      math.Y1,
 		"Yn":      math.Yn,
 	}
-	PackageTypes["math"] = map[string]interface{}{}
 	init_math()
-
 }
diff --git a/packages/math.rand.110.go b/packages/math.rand.110.go
index 6994fb69..c8fa7329 100644
--- a/packages/math.rand.110.go
+++ b/packages/math.rand.110.go
@@ -7,7 +7,5 @@ import (
 )
 
 func init_math_rand() {
-
 	Packages["math/rand"]["Shuffle"] = rand.Shuffle
-
 }
diff --git a/packages/math.rand.18.go b/packages/math.rand.18.go
index 9fd5bb17..5e7467e1 100644
--- a/packages/math.rand.18.go
+++ b/packages/math.rand.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.10
+// +build !go1.10
 
 package packages
 
diff --git a/packages/math.rand.go b/packages/math.rand.go
index 63f6f3f6..66487f75 100644
--- a/packages/math.rand.go
+++ b/packages/math.rand.go
@@ -37,5 +37,4 @@ func init() {
 		"Zipf":     reflect.TypeOf(&zipf).Elem(),
 	}
 	init_math_rand()
-
 }
diff --git a/packages/net.go b/packages/net.go
index ff276c8e..0e01fb61 100644
--- a/packages/net.go
+++ b/packages/net.go
@@ -140,5 +140,4 @@ func init() {
 		"UnixListener":        reflect.TypeOf(&unixlistener).Elem(),
 		"UnknownNetworkError": reflect.TypeOf(&unknownnetworkerror).Elem(),
 	}
-
 }
diff --git a/packages/net.http.18.go b/packages/net.http.18.go
index 26e734fd..73f67d03 100644
--- a/packages/net.http.18.go
+++ b/packages/net.http.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.9,!go1.10
+// +build !go1.9
 
 package packages
 
diff --git a/packages/net.http.19.110.go b/packages/net.http.19.go
similarity index 82%
rename from packages/net.http.19.110.go
rename to packages/net.http.19.go
index ccb7b178..7730b71d 100644
--- a/packages/net.http.19.110.go
+++ b/packages/net.http.19.go
@@ -1,4 +1,4 @@
-// +build go1.9 go1.10
+// +build go1.9
 
 package packages
 
@@ -7,7 +7,5 @@ import (
 )
 
 func init_net_http() {
-
 	Packages["net/http"]["ServeTLS"] = http.ServeTLS
-
 }
diff --git a/packages/net.http.cookiejar.go b/packages/net.http.cookiejar.go
index 3cccff36..e20b4031 100644
--- a/packages/net.http.cookiejar.go
+++ b/packages/net.http.cookiejar.go
@@ -17,5 +17,4 @@ func init() {
 		"Options":          reflect.TypeOf(&options).Elem(),
 		"PublicSuffixList": reflect.TypeOf(&publicsuffixlist).Elem(),
 	}
-
 }
diff --git a/packages/net.http.go b/packages/net.http.go
index e357a701..c53f19f4 100644
--- a/packages/net.http.go
+++ b/packages/net.http.go
@@ -194,5 +194,4 @@ func init() {
 		"Transport":      reflect.TypeOf(&transport).Elem(),
 	}
 	init_net_http()
-
 }
diff --git a/packages/net.url.go b/packages/net.url.go
index 01c61a2e..173eb6f6 100644
--- a/packages/net.url.go
+++ b/packages/net.url.go
@@ -31,5 +31,4 @@ func init() {
 		"Userinfo":         reflect.TypeOf(&userinfo).Elem(),
 		"Values":           reflect.TypeOf(&values).Elem(),
 	}
-
 }
diff --git a/packages/os.110.go b/packages/os.110.go
index f74028bc..8dee3592 100644
--- a/packages/os.110.go
+++ b/packages/os.110.go
@@ -7,9 +7,6 @@ import (
 )
 
 func init_os() {
-
 	Packages["os"]["ErrNoDeadline"] = os.ErrNoDeadline
-
 	Packages["os"]["IsTimeout"] = os.IsTimeout
-
 }
diff --git a/packages/os.18.go b/packages/os.18.go
index 8df48e2d..8ad8d10d 100644
--- a/packages/os.18.go
+++ b/packages/os.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.10
+// +build !go1.10
 
 package packages
 
diff --git a/packages/os.exec.go b/packages/os.exec.go
index bc90da25..98e2ffb6 100644
--- a/packages/os.exec.go
+++ b/packages/os.exec.go
@@ -20,5 +20,4 @@ func init() {
 		"Error":     reflect.TypeOf(&error_).Elem(),
 		"ExitError": reflect.TypeOf(&exiterror).Elem(),
 	}
-
 }
diff --git a/packages/os.go b/packages/os.go
index da77ab73..e1c9a10c 100644
--- a/packages/os.go
+++ b/packages/os.go
@@ -120,5 +120,4 @@ func init() {
 		"SyscallError": reflect.TypeOf(&syscallerror).Elem(),
 	}
 	init_os()
-
 }
diff --git a/packages/os.signal.go b/packages/os.signal.go
index 21d6a667..baf33e48 100644
--- a/packages/os.signal.go
+++ b/packages/os.signal.go
@@ -11,6 +11,4 @@ func init() {
 		"Reset":  signal.Reset,
 		"Stop":   signal.Stop,
 	}
-	PackageTypes["os/signal"] = map[string]interface{}{}
-
 }
diff --git a/packages/path.filepath.go b/packages/path.filepath.go
index f62a0b34..3a243a39 100644
--- a/packages/path.filepath.go
+++ b/packages/path.filepath.go
@@ -34,5 +34,4 @@ func init() {
 	PackageTypes["path/filepath"] = map[string]interface{}{
 		"WalkFunc": reflect.TypeOf(&walkfunc).Elem(),
 	}
-
 }
diff --git a/packages/path.go b/packages/path.go
index e8027e26..6ab6ad6a 100644
--- a/packages/path.go
+++ b/packages/path.go
@@ -16,6 +16,4 @@ func init() {
 		"Match":         path.Match,
 		"Split":         path.Split,
 	}
-	PackageTypes["path"] = map[string]interface{}{}
-
 }
diff --git a/packages/regexp.go b/packages/regexp.go
index 4ba35942..9921f055 100644
--- a/packages/regexp.go
+++ b/packages/regexp.go
@@ -20,5 +20,4 @@ func init() {
 	PackageTypes["regexp"] = map[string]interface{}{
 		"Regexp": reflect.TypeOf(&regexp_).Elem(),
 	}
-
 }
diff --git a/packages/runtime.go b/packages/runtime.go
index 82e3cda7..4a960e23 100644
--- a/packages/runtime.go
+++ b/packages/runtime.go
@@ -65,5 +65,4 @@ func init() {
 		"StackRecord":        reflect.TypeOf(&stackrecord).Elem(),
 		"TypeAssertionError": reflect.TypeOf(&typeassertionerror).Elem(),
 	}
-
 }
diff --git a/packages/sort.go b/packages/sort.go
index 91bfb335..d78e1559 100644
--- a/packages/sort.go
+++ b/packages/sort.go
@@ -15,7 +15,6 @@ type SortFuncsStruct struct {
 func (s SortFuncsStruct) Len() int           { return s.LenFunc() }
 func (s SortFuncsStruct) Less(i, j int) bool { return s.LessFunc(i, j) }
 func (s SortFuncsStruct) Swap(i, j int)      { s.SwapFunc(i, j) }
-
 func init() {
 	var float64slice sort.Float64Slice
 	var intslice sort.IntSlice
@@ -47,5 +46,4 @@ func init() {
 		"StringSlice":     reflect.TypeOf(&stringslice).Elem(),
 		"SortFuncsStruct": &SortFuncsStruct{},
 	}
-
 }
diff --git a/packages/strconv.go b/packages/strconv.go
index 0eb5d217..bbada45c 100644
--- a/packages/strconv.go
+++ b/packages/strconv.go
@@ -46,5 +46,4 @@ func init() {
 	PackageTypes["strconv"] = map[string]interface{}{
 		"NumError": reflect.TypeOf(&numerror).Elem(),
 	}
-
 }
diff --git a/packages/strings.110.go b/packages/strings.110.go
index 8ca52169..54c5c09e 100644
--- a/packages/strings.110.go
+++ b/packages/strings.110.go
@@ -9,7 +9,5 @@ import (
 
 func init_strings() {
 	var builder strings.Builder
-
 	PackageTypes["strings"]["Builder"] = reflect.TypeOf(&builder).Elem()
-
 }
diff --git a/packages/strings.18.go b/packages/strings.18.go
index f05cd2b1..13d61bcc 100644
--- a/packages/strings.18.go
+++ b/packages/strings.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.10
+// +build !go1.10
 
 package packages
 
diff --git a/packages/strings.go b/packages/strings.go
index 13821a59..9b3a011b 100644
--- a/packages/strings.go
+++ b/packages/strings.go
@@ -60,5 +60,4 @@ func init() {
 		"Replacer": reflect.TypeOf(&replacer).Elem(),
 	}
 	init_strings()
-
 }
diff --git a/packages/time.110.go b/packages/time.110.go
index e4fc55c8..f85c6dc9 100644
--- a/packages/time.110.go
+++ b/packages/time.110.go
@@ -7,7 +7,5 @@ import (
 )
 
 func init_time() {
-
 	Packages["time"]["LoadLocationFromTZData"] = time.LoadLocationFromTZData
-
 }
diff --git a/packages/time.18.go b/packages/time.18.go
index 938f2ca1..c746f35d 100644
--- a/packages/time.18.go
+++ b/packages/time.18.go
@@ -1,4 +1,4 @@
-// +build go1.8,!go1.10
+// +build !go1.10
 
 package packages
 
diff --git a/packages/time.go b/packages/time.go
index ae654dae..234e8dc3 100644
--- a/packages/time.go
+++ b/packages/time.go
@@ -85,5 +85,4 @@ func init() {
 		"Weekday":    reflect.TypeOf(&weekday).Elem(),
 	}
 	init_time()
-
 }