Recipe 1.1. Processing a String One Character at a Time(Python Cookbook)

 >>> import sets

 >>> magic_chars = sets.set('abracadabra')

 >>> magic_chars = sets.Set('abracadabra')

 >>> poppins_chars = sets.Set('supercalifragilisticexpialidocious')

 >>> print ''.join(magic_chars & poppins_chars)

 acrd

 

 >>> def fun(c):
2     print c
3     
4 >>> map(fun, "abc")
5 a
6 b
7 c
8 [None, None, None]