code: def _postprocess_hover(self, renderer, source):
          
          hover = self.handles.get('hover')
          if hover is None:
              return
          if hover.renderers == 'auto':
              hover.renderers = []
          hover.renderers.append(renderer)
  
          # If datetime column is in the data replace hover formatter
          for k, v in source.data.items():
              if k+'_dt_strings' in source.data:
                  tooltips = []
                  for name, formatter in hover.tooltips:
                      if formatter == '@{%s}' % k:
                          formatter = '@{%s_dt_strings}' % k
                      tooltips.append((name, formatter))
                  hover.tooltips = tooltips
docs: Attaches renderer to hover tool and processes tooltips to
          ensure datetime data is displayed correctly.