import sets 
magic_chars = sets.Set('abracadabra') 
print magic_chars 
poping_chars = sets.Set('supercalifragilisticeexpialidocious') 
print poping_chars 
print "".join(magic_chars & poping_chars)

Set(['a', 'r', 'b', 'c', 'd'])
Set(['a', 'c', 'e', 'd', 'g', 'f', 'i', 'l', 'o', 'p', 's', 'r', 'u', 't', 'x'])
acrd