HELP plz , python class & function

Question

I saw this example but I don't know how the function would work!!
my problem is in this line :
def send(self, data: bytes) -> bytes:
could somebody explain what happens in this function??(spatially in this part:
"data: bytes) -> bytes:")

class CommunicationChannel(object):
def __init__(self, args):
self.args = args

def send(self, data: bytes) -> bytes:
raise NotImplementedError()

Answer 1

okay I got it
object is a parent for all of the python classes
and ":" is to define input type and "->" is to define the output type

Answer 2

Yes