class Pipe:
  def __init__(self):
    self.data=[]

  # the pipe is true if there are data in it
  def __nonzero__(self):
    return bool(self.data)

  def read(self):
    return self.data.pop()

  def write(self,item):
    self.data.append(item)

def feeder(pipe):
  while True:
    if not pipe:
      pipe.write(1)

thePipe=Pipe()

import thread
thread.start_new_thread(feeder,(thePipe,))

while True:
  if thePipe and thePipe.read()==2: # should be false!
    print "How can this happen?"