title: How to get Bokeh to interpolate a palette from 3 colors
body: <p>I built a heatmap in Bokeh which works fine. I want it to be colored from bright green to bright red, continuously. The current code is:</p>
  <pre><code>colors = [&quot;#66ff00&quot;, &quot;#FFFFFF&quot;, &quot;#FF0000&quot;]
  colors.reverse()
  mapper = LinearColorMapper(palette=colors, low=-50, high=50)
  
  p.rect(..., fill_color=transform('percentage', mapper))
  </code></pre>
  <p>The problem is that only 3 colors are appearing in the heatmap. I would expect all values between -50 and 50 to linearly interpolate the values between bright red to white to bright green and show up in the heatmap. How can I achieve this?</p>