Permutations in Python

perm.py

def permutations(s):
    """Return all permutations of the characters in a string."""
    res = []
    for i in xrange(len(s)):
        c = s[i]
        rem = s[:i] + s[i+1:]
        if rem:
            temp = permutations(rem)
            res += [c + t for t in temp]
        else:
            res += c
    return res