def binary_string(number: int) -> str:
    """Number to binary string

    :param number: some number (an integer) to turn into a binary string
    :return: Some string which is the binary string
    :rtype: str

    .. doctest:: python

        >>> binary_string(200)
        '11001000'
        >>> binary_string(10)
        '1010'

    """
    return bin(number)[2:]