I cannot figure out how to fix this problem, can someone help me ? Pirple homework python

Create a global variable called myUniqueList. It should be an empty list to start.

Next, create a function that allows you to add things to that list. Anything that’s passed to this function should get added to myUniqueList, unless its value already exists in myUniqueList. If the value doesn’t exist already, it should be added and the function should return True. If the value does exist, it should not be added, and the function should return False;

extra is if we can make the remaining values to a list called my leftovers

myUniqueList = ()
myLeftovers = ()

def addUniqueElement(b):
if b not in myUniqueList:
return True
return False