How to determine whether a list contains an element in python

In python, you can use the in and not in keywords to determine whether a list contains an element

pythontab = ['p','y','t','h','o','n','t','a','b']
if 't' in pythontab:
    print 't in pythontab'
if 'w' not in pythontab:
    print 'w is not in pythontab'

in and not in are very commonly used keywords.