memoized fibonacci function in Python

fib.py

import datetime


def fib(a):
  if (a>2):
    return fib(a-1) + fib (a-2)
  elif (a==1 or a==2):
    return 1
  elif (a<1):
    return 0


def memoFibb():
  fibs={}
  def f(a):
    if (fibs.has_key(a)):
      return fibs[a]
    elif (a>2):
      fibs[a]=f(a-1)+f(a-2)
      return fibs[a]
    elif (a==1 or a==2):
      return 1
    elif (a<1):
      return 0
  return f


def timeProc(proc, arg):
  sd=datetime.datetime.now()
  print "start", sd
  f=proc(arg)
  sd2=datetime.datetime.now()
  print "end", sd2
  print "it took", sd2-sd
  print "the answer is", f


"""
memoFibb runs many orders of magnitude faster than fib

>>> timeProc(memoFibb(),35)
start 2014-05-15 17:35:54.883773
end 2014-05-15 17:35:54.883773
it took 0:00:00
the answer is 9227465

>>> timeProc(fib,35)
start 2014-05-15 17:35:59.537773
end 2014-05-15 17:36:01.763773
it took 0:00:02.226000
the answer is 9227465

"""