Helper function that builds and md5sum from a file in chunks.

    Args:
        file_path: The path to the file you want an md5sum for.

    Returns:
        A string containing an md5sum.

def _md5sum(file_path):
    """ Helper function that builds and md5sum from a file in chunks.

    Args:
        file_path: The path to the file you want an md5sum for.

    Returns:
        A string containing an md5sum.

    """
    md5 = hashlib.md5()

    with open(file_path, "rb") as md5_file:
        while True:
            data = md5_file.read(1024 * 1024 * 4)
            if not data:
                break
            md5.update(data)

    return md5.digest()