Swap between list of bytes and integer value

int_bytes.py

def bytes2int(b):
    """Convert list/tuple of two bytes to integer value"""
    if len(b) != 2: raise ValueError('b must have exactly 2 items')
    return (b[0] << 8) + b[1]


def int2bytes(i):
    """Convert integer value to list of bytes"""
    if i > 0xFFFF:
        raise ValueError()
    return [i >> 8, i & 0x00FF]