perm1.py

def perm(s = [], beg = 0, end = 0):
    if (len (s) == 0):
        return;

    if ( beg == end ):
        print s
    else:
        for i in xrange(beg, end):
            temp = s[i]
            s[i] = s[beg]
            s[beg] = temp

            perm(s, beg+1, end)

            temp = s[i]
            s[i] = s[beg]
            s[beg] = temp