how to get common of 2 list in ptyhon code example

Example 1: find common words in two lists python

list1 = ['little','blue','widget']
list2 = ['there','is','a','little','blue','cup','on','the','table']

list3 = set(list1)&set(list2)

list4 = sorted(list3, key = lambda k : list1.index(k))

Example 2: same elements of two sets in python

x = {2, 3, 5, 6}
y = {1, 2, 3, 4}

z = x.intersection(y)