code: def _dynamic_mul(self, dimensions, other, keys):
          
          # If either is a HoloMap compute Dimension values
          if not isinstance(self, DynamicMap) or not isinstance(other, DynamicMap):
              keys = sorted((d, v) for k in keys for d, v in k)
              grouped =  dict([(g, [v for _, v in group])
                               for g, group in groupby(keys, lambda x: x[0])])
              dimensions = [d(values=grouped[d.name]) for d in dimensions]
              map_obj = None
  
          # Combine streams
          map_obj = self if isinstance(self, DynamicMap) else other
          if isinstance(self, DynamicMap) and isinstance(other, DynamicMap):
              self_streams = util.dimensioned_streams(self)
              other_streams = util.dimensioned_streams(other)
              streams = list(util.unique_iterator(self_streams+other_streams))
          else:
              streams = map_obj.streams
  
          def dynamic_mul(*key, **kwargs):
              key_map = {d.name: k for d, k in zip(dimensions, key)}
              layers = []
              try:
                  self_el = self.select(HoloMap, **key_map) if self.kdims else self[()]
                  layers.append(self_el)
              except KeyError:
                  pass
              try:
                  other_el = other.select(HoloMap, **key_map) if other.kdims else other[()]
                  layers.append(other_el)
              except KeyError:
                  pass
              return Overlay(layers)
          callback = Callable(dynamic_mul, inputs=[self, other])
          callback._is_overlay = True
          if map_obj:
              return map_obj.clone(callback=callback, shared_data=False,
                                   kdims=dimensions, streams=streams)
          else:
              return DynamicMap(callback=callback, kdims=dimensions,
                                streams=streams)
docs: Implements dynamic version of overlaying operation overlaying
          DynamicMaps and HoloMaps where the key dimensions of one is
          a strict superset of the other.