code: def _dataslice(self, data, indices):
          
          if self._deep_indexable and isinstance(data, Dimensioned) and indices:
              return data[indices]
          elif len(indices) > 0:
              self.param.warning('Cannot index into data element, extra data'
                                 ' indices ignored.')
          return data
docs: Returns slice of data element if the item is deep
          indexable. Warns if attempting to slice an object that has not
          been declared deep indexable.