import random
import time


def rndstr(length):
    return ''.join(random.choice('0123456789abcdef') for i in range(length))


def choice(arr):
    return random.choice(arr)


def rndunicode():
    return chr(random.randint(0, 0x10FFFF))


def choice_percent(elements):
    # elements is a dict of {percent: action}
    # like following:
    # elements = {
    #     10: lambda: 'a',
    #     20: lambda: 'b',
    #     30: lambda: 'c',
    #     40: lambda: 'd',
    # }
    # that means we have 10% chance to get 'a', 20% chance to get 'b', etc.

    # get total percent
    total_percent = 0
    for percent in elements:
        total_percent += percent

    # get random number
    random.seed(int(time.time() * 1000))
    rnd = random.randint(0, total_percent)

    # get action
    for percent in elements:
        if rnd < percent:
            return elements[percent]
        else:
            rnd -= percent

    # should not reach here
    return None