#!/usr/bin/env python

# wherever you see 'L' below, pretend
# that it is the lambda symbol.

# this is essentially the same program as
# (Lx.Ly.yx)xy
def swap2(x):
  def swap1(y):
    return (y,x)
  return swap1

# see, the program swaps "a" and "b"
print(swap2("a")("b"))

# but we can also do it in two steps
# here, swap2 returns a function, which
# is waiting for one more argument
f = swap2("a")
print(f)

# we give it one more argument
print(f("b"))