third gist for https://medium.com/p/c4e88a6edb87/edit

main.go

package main

import (
	"go/parser"
	"go/token"
	"log"

  "github.com/davecgh/go-spew/spew"
)

func main() {
	fs := token.NewFileSet()
	f, err := parser.ParseFile(fs, "", "package main; var a = 3", parser.AllErrors)
	if err != nil {
		log.Fatal(err)
	}
	spew.Dump(f)
}