def fac(x):
  if n == 0:return 1
  else:return x*fac(x-1)

reduce(lambda n m :n*m,range(1,x+1))

def func1():
  print 'func1'
  func2()

def func2():
  print 'func2'
  func1()

func1()

import stackless
channel_1 = stackless.channel()
channel_2 = stackless.channel()
def func1():
  while channel_1.receive():
   print 'func1'
   channel_2.send('heelo,func2,it's your turn')

def func2():
  while channel_2.receive():
   print 'func1'
   channel_1.send('heelo,func1,it's your turn')


stackless.tasklet(func1)()
stackless.tasklet(func2)()
stackless.tasklet(channel_1.send)('go')
stackless.run()