Task: 21 game
Go: package main

import (
    "bufio"
    "fmt"
    "log"
    "math/rand"
    "os"
    "strconv"
    "time"
)

var scanner = bufio.NewScanner(os.Stdin)

var (
    total = 0
    quit  = false
)

func itob(i int) bool {
    if i == 0 {
        return false
    }
    return true
}

func getChoice() {
    for {
        fmt.Print("Your choice 1 to 3 : ")
        scanner.Scan()
        if scerr := scanner.Err(); scerr != nil {
            log.Fatalln(scerr, "when choosing number")
        }
        text := scanner.Text()
        if text == "q" || text == "Q" {
            quit = true
            return
        }
        input, err := strconv.Atoi(text)
        if err != nil {
            fmt.Println("Invalid number, try again")
            continue
        }
        newTotal := total + input
        switch {
        case input < 1 || input > 3:
            fmt.Println("Out of range, try again")
        case newTotal > 21:
            fmt.Println("Too big, try again")
        default:
            total = newTotal
            fmt.Println("Running total is now", total)
            return
        }
    }
}

func main() {
    rand.Seed(time.Now().UnixNano())
    computer := itob(rand.Intn(2))
    fmt.Println("Enter q to quit at any time\n")
    if computer {
        fmt.Println("The computer will choose first")
    } else {
        fmt.Println("You will choose first")
    }
    fmt.Println("\nRunning total is now 0\n")
    var choice int
    for round := 1; ; round++ {
        fmt.Printf("ROUND %d:\n\n", round)
        for i := 0; i < 2; i++ {
            if computer {
                if total < 18 {
                    choice = 1 + rand.Intn(3)
                } else {
                    choice = 21 - total
                }
                total += choice
                fmt.Println("The computer chooses", choice)
                fmt.Println("Running total is now", total)
                if total == 21 {
                    fmt.Println("\nSo, commiserations, the computer has won!")
                    return
                }
            } else {
                getChoice()
                if quit {
                    fmt.Println("OK, quitting the game")
                    return
                }
                if total == 21 {
                    fmt.Println("\nSo, congratulations, you've won!")
                    return
                }
            }
            fmt.Println()
            computer = !computer
        }
    }
}

Python: from random import randint
def start():
	game_count=0
	print("Enter q to quit at any time.\nThe computer will choose first.\nRunning total is now {}".format(game_count))
	roundno=1
	while game_count<21:
		print("\nROUND {}: \n".format(roundno))
		t = select_count(game_count)
		game_count = game_count+t
		print("Running total is now {}\n".format(game_count))
		if game_count>=21:
			print("So, commiserations, the computer has won!")
			return 0
		t = request_count()
		if not t:
			print('OK,quitting the game')
			return -1
		game_count = game_count+t
		print("Running total is now {}\n".format(game_count))
		if game_count>=21:
			print("So, congratulations, you've won!")
			return 1
		roundno+=1

def select_count(game_count):
	
	if game_count<18:
		t= randint(1,3)
	else:
		t = 21-game_count
	print("The computer chooses {}".format(t))
	return t

def request_count():
	
	t=""
	while True:
		try:
			t = raw_input('Your choice 1 to 3 :')
			if int(t) in [1,2,3]:
				return int(t)
			else:
				print("Out of range, try again")
		except:
			if t=="q":
				return None
			else:
				print("Invalid Entry, try again")

c=0
m=0
r=True
while r:
	o = start()
	if o==-1:
		break
	else:
		c+=1 if o==0 else 0
		m+=1 if o==1 else 0
	print("Computer wins {0} game, human wins {1} games".format(c,m))
	t = raw_input("Another game?(press y to continue):")
	r = (t=="y")