package main

import (
	"fmt"
)

var balance float64 = 0

func main() {
	deposit(.1)
	deposit(.2)
	if balance, ok := withdraw(0.30000000000000004); ok {
		fmt.Println(balance)
	}
}


func deposit(v float64) {
	balance += v
}

func withdraw(v float64) (float64, bool) {
	if v <= balance {
		balance -= v
		return v, true
	}
	
	return  0, false
}