What is a pad byte (x) in the python struct type? Is it an unsigned char with value 0, or what exactly does it look like / why is it one of the types that are available in the struct object?
For example, what would be the difference between doing one of the following:
>>> struct.pack('BB', 0, ord('a'))
b'\x00a'
>>> struct.pack('xB', ord('a'))
b'\x00a'