gistfile1.py

import sys

def _each(f, xs):
  x = xs[0]
  f(x)
  if xs[1:]:
    _each(f, xs[1:])


def _shortest(i, *rs):
  def f(r):
    try:
      x = r[i]
    except IndexError:
      print r
      sys.exit(0)
  _each(f, rs)
  _shortest(i+1, *rs)

def shortest_r(*rs):
    _shortest(0, *rs)

print shortest_r([1, 2], [3, 4, 5], [6, 7])

pythonで再代入・破壊変更禁止(for文禁止)は苦しいね。