#By Robin Wellner (gvx)
#I hereby waive copyright and related or neighboring rights to this work
#See the Creative Commons Zero Waiver at <http://creativecommons.org/publicdomain/zero/1.0/>

def switch(expression, cases, default=None):
    try:
        ret = cases[expression]
    except KeyError:
        ret = default
    if callable(ret): ret = ret()
    return ret