code: def include_in_layout(self):
          
          overlay = self._element.overlay
          if overlay is None:
              return True
          return overlay.val
docs: |True| if legend should be located inside plot area.
  
          Read/write boolean specifying whether legend should be placed inside
          the plot area. In many cases this will cause it to be superimposed on
          the chart itself. Assigning |None| to this property causes any
          `c:overlay` element to be removed, which is interpreted the same as
          |True|. This use case should rarely be required and assigning
          a boolean value is recommended.