Splat operator (aka *) allows a function to receive any number or arguments.

def mysum(*numbers):
    print(type(numbers))  # tuple
 
mysum(1,2,3,4,5)     # passing arbitrary number of arguments
mysum(*[2,3,4,5,6])  # unpacking an iterable

A generator expression looks just like a list comprehension but with parentheses instead of brackets:

# List comprehension — builds a list
[pig_latin(w) for w in s.split()]
 
# Generator expression — produces values lazily
(pig_latin(w) for w in s.split())