clojure.walk in Python

gistfile1.py

from functools import partial

def identity(e):
    return e

def walk(inner, outer, coll):
    if isinstance(coll, list):
        return outer([inner(e) for e in coll])
    elif isinstance(coll, dict):
        return outer(dict([inner(e) for e in coll.iteritems()]))
    elif isinstance(coll, tuple):
        return outer([inner(e) for e in coll])
    else:
        return outer(coll)

def prewalk(fn, coll):
    return walk(partial(prewalk, fn), identity, fn(coll))

def postwalk(fn, coll):
    return walk(partial(postwalk, fn), fn, coll)

def prewalk_demo(coll):
    def prn(e):
        print "Walked:", e
        return e
    return prewalk(prn, coll)

def postwalk_demo(coll):
    def prn(e):
        print "Walked:", e
        return e
    return postwalk(prn, coll)

Amazing thank you.
Needs update for python3:
10. return outer(dict([inner(e) for e in coll.iteritems()])) => return outer(dict([inner(e) for e in coll.items()]))
24. print "Walked:", e => print("Walked:", e)
30. print "Walked:", e => print("Walked:", e)