Computing permutations with a recursive generator expression

#!/usr/bin/python2.5
def permute(li):
    """Generate all permutations of a sequence
    >>> for i in permute([1,2,3]): print i
    (1, 2, 3)
    (1, 3, 2)
    (2, 1, 3)
    (2, 3, 1)
    (3, 1, 2)
    (3, 2, 1)"""
    return ((i,)+j for i in li for j in (permute([k for k in li if k is not i])
                                         if len(li) > 1 else [()] ) )

import doctest
doctest.testmod(verbose=True)