TypeError: collection.item.map(...).flat is not a function

[M-Mortaz]

Hi, I'm using example code from the doc but I'm getting the error:

➜  postman_to_swagger node run.js
/home/parsezan/work/postman_to_swagger/node_modules/postman-to-swagger/src/to_swagger_2.0.js:51
    .flat(1)
     ^

TypeError: collection.item.map(...).flat is not a function
    at getPaths (/home/parsezan/work/postman_to_swagger/node_modules/postman-to-swagger/src/to_swagger_2.0.js:51:6)
    at module.exports (/home/parsezan/work/postman_to_swagger/node_modules/postman-to-swagger/src/to_swagger_2.0.js:41:18)
    at module.exports (/home/parsezan/work/postman_to_swagger/node_modules/postman-to-swagger/src/index.js:32:16)
    at Object.<anonymous> (/home/parsezan/work/postman_to_swagger/run.js:5:21)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)

Node: v10.19.0
Npm: 6.14