title: Only show Hover Tooltip for One Glyph in Python bokeh
body: <p>I want to have my hovertool, showing only when I hover above the diamonds. As you will see my plot contains diamonds and lines.</p>
  
  <pre><code>tooltips = [("Year", "@x{0}"), ("Numbers", "@y{0}")]
  p = figure(plot_width=800, plot_height=400,tooltips=tooltips)
  p.diamond(df3reset["Years"], df3reset["Numbers"], size=20,
  color="navy", alpha=0.5)
  p.line(df3reset["Years"], df3reset["Numbers"], line_width=2)
  p.xaxis.axis_label = 'Year'
  p.yaxis.axis_label = 'Number of dogs'
  show(p)
  </code></pre>
  
  <p>I dont want the hovertool to show the information on the line only while hovering over the diamonds, what would be the solution?</p>
  
  <p>Greetings</p>