This code works perfectly:

b'\x4a' + b'\x20'
b'J '

But this doesn’t:

sum([b'\x4a', b'\x20'])
TypeError: unsupported operand type(s) for +: 'int' and 'bytes'

Why? How to concatenate many bytes elements?

>Solution :

You can use join instead:

b''.join([b'\x4a', b'\x20'])

Output:

b'J '