od makes use of the standard Python's zlib and base64 libraries.

    *Examples:*

    >>> n = 0 # <- ignore this, it's a fix for Pycharm (not fixable using ignore comments)
    >>> # "original" will be a string with 169 chars:
    >>> original = ' '.join(['word n{}'.format(n) for n in range(20)])
    >>> # "compressed" will be a string of 88 chars
    >>> compressed = compress(original)

    :param input_string: String to compress (must be not empty or a ValueError will be raised).
    :type input_string: str
    :param encoding: String encoding (default to "utf-8").
    :type encoding: str
    :param compression_level: A value between 0 (no compression) and 9 (best compression), default to 9.
    :type compression_level: int
    :return: Compressed string.
    )