Write function to customer design doc

[lufishggg]

Have you ever consider write some methods to customer design doc? For example, there is a query doc:

doc, _ := gqlparser.LoadQuery(parsedSchema, "mutation($text: String!, $userId: String!) {createTodo(input: {text: $text, userId: $userId}) {id}}")

we can customer design and change the doc ( remove or and some selection, remove or add some arguments), something like:

addArguments(doc, "key"), then the doc will be:

var buf bytes.Buffer
formatter.NewFormatter(&buf).FormatQueryDocument(doc)
fmt.Println(buf.String())

output:
mutation($text: String!, $userId: String!, $key: String!) {createTodo(input: {text: $text, userId: $userId, key: $key}) {id}}"