Permutation ohne Doubletten

#!/usr/bin/python
def perm(source, done=0, current=[]):
   if done == len(source): 
      if current[0] < current[-1]: 
         print current
   else:
      for i in source:
         if i not in current:
            perm(source, done+1, current+[i])

d = [1,2,3,4]
perm(d)