code: def update(self, *others):
          r
          _elements = self._elements
          for other in map(self._as_mapping, others):
              for element, multiplicity in other.items():
                  self[element] += multiplicity
docs: r"""Like :meth:`dict.update` but add multiplicities instead of replacing them.
  
          >>> ms = Multiset('aab')
          >>> ms.update('abc')
          >>> sorted(ms)
          ['a', 'a', 'a', 'b', 'b', 'c']
  
          Note that the operator ``+=`` is equivalent to :meth:`update`, except that the operator will only
          accept sets to avoid accidental errors.
  
          >>> ms += Multiset('bc')
          >>> sorted(ms)
          ['a', 'a', 'a', 'b', 'b', 'b', 'c', 'c']
  
          For a variant of the operation which does not modify the multiset, but returns a new
          multiset instead see :meth:`combine`.
  
          Args:
              others: The other sets to add to this multiset. Can also be any :class:`~typing.Iterable`\[~T]
                  or :class:`~typing.Mapping`\[~T, :class:`int`] which are then converted to :class:`Multiset`\[~T].