code: def hr_diagram_figure(cluster):
      
      temps, lums = round_teff_luminosity(cluster)
      x, y = temps, lums
      colors, color_mapper = hr_diagram_color_helper(temps)
      x_range = [max(x) + max(x) * 0.05, min(x) - min(x) * 0.05]
      source = ColumnDataSource(data=dict(x=x, y=y, color=colors))
  
      pf = figure(y_axis_type='log', x_range=x_range, name='hr',
                  tools='box_select,lasso_select,reset,hover',
                  title='H-R Diagram for {0}'.format(cluster.name))
      pf.select(BoxSelectTool).select_every_mousemove = False
      pf.select(LassoSelectTool).select_every_mousemove = False
      hover = pf.select(HoverTool)[0]
      hover.tooltips = [("Temperature (Kelvin)", "@x{0}"),
                        ("Luminosity (solar units)", "@y{0.00}")]
      _diagram(source=source, plot_figure=pf, name='hr',
               color={'field': 'color', 'transform': color_mapper},
               xaxis_label='Temperature (Kelvin)',
               yaxis_label='Luminosity (solar units)')
      return pf
docs: Given a cluster create a Bokeh plot figure creating an
      H-R diagram.