def _pack_bytes(byte_list):
    """Packs a list of bytes to be a single unsigned int.

    The MSB is the leftmost byte (index 0).
    The LSB is the rightmost byte (index -1 or len(byte_list) - 1).
    Big Endian order.
    Each value in byte_list is assumed to be a byte (range [0, 255]).
    This assumption is not validated in this function.

    Args:
        byte_list (list):

    Returns:
        The number resulting from the packed bytes.
    """
    return int.from_bytes(byte_list, 'big', signed=False)