docs: def pop(self, key, default=NotDefined):
          # type: (Hashable, Any) -> Any
          """
          Pop the last item for a list on the dict.  Afterwards the
          key is removed from the dict, so additional values are discarded:
          >>> d = MultiValueDict({"foo": [1, 2, 3]})
          >>> d.pop("foo")
          1
          >>> "foo" in d
          False
  
          :param key: the key to pop.
          :param default: if provided the value to return if the key was
                          not in the dictionary.
          """
          try:
              return dict.pop(self, key)[-1]
          except LookupError:
              if default is NotDefined:
                  raise MultiValueDictKeyError(key)
              return default