how to get common elements from two lists in python 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: find number of common element in two python array

len([x for x in list1 if x in list2])