How can I compare two lists in python and return matches

Question

I want to take two lists and find the values that appear in both.

a = [1, 2, 3, 4, 5]
b = [9, 8, 7, 6, 5]

returnMatches(a, b)

would return

Answer 1

Also you can try this,by keeping common elements in a new list.

new_list = []
for element in a:
    if element in b:
        new_list.append(element)