base36.py

def base36encode(integer):
    chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    sign = '-' if integer < 0 else ''
    integer = abs(integer)
    result = ''

    while integer > 0:
        integer, remainder = divmod(integer, 36)
        result = chars[remainder] + result

    return sign + result