code: def popitem(self, last=True):
          
          if not len(self):
              raise KeyError('popitem(): dictionary is empty')
  
          key = self._list_pop(-1 if last else 0)
          value = self._pop(key)
  
          return (key, value)
docs: Remove and return a ``(key, value)`` pair from the dictionary. If
          last=True (default) then remove the *greatest* `key` from the
          diciontary. Else, remove the *least* key from the dictionary.
  
          If the dictionary is empty, calling `popitem` raises a
          KeyError`.