package main

import (
    "bufio"
    "errors"
    "fmt"
    "go/ast"
    "go/parser"
    "go/token"
    "os"
    "reflect"
)

func main() {
    in := bufio.NewScanner(os.Stdin)
    for {
        fmt.Print("Expr:  ")
        in.Scan()
        if err := in.Err(); err != nil {
            fmt.Println(err)
            return
        }
        if !tt(in.Text()) {
            return
        }
    }
}

func tt(expr string) bool {