Why create an empty tuple "tp=()" if I can't assign values to it later on? What useful function could I get out of an empty tuple?

Answer 1

It could be a replacement for None where a tuple is needed.

Answer 2

But can't I assign None where a tuple is needed?

Answer 3

You could in many situations, but there are some cases that it's more convenient to specify an empty tuple or list -- like as a default value for a function parameter where you expect a tuple.