def get_zero_mask(number: int, max_len: int = 3) -> str:
    """
    Returns string of numbers formated with zero mask
    eg.
    >>> get_zero_mask(100, 4)
    '0100'
    >>> get_zero_mask(101, 4)
    '0101'
    >>> get_zero_mask(101, 4)
    '0101'
    """
    return f'%0.{max_len}d' % number