code: def pop(self, key, default=None):
          
          with self.lock:
              try:
                  item = OrderedDict.__getitem__(self, key)
                  del self[key]
                  return item[0]
              except KeyError:
                  return default
docs: Get item from the dict and remove it.
  
          Return default if expired or does not exist. Never raise KeyError.