title: set title of a python `bokeh` plot figure from outside of the `figure()` function
body: <p>I ran into a very seemingly simple problem when using the <code>bokeh</code> plotting package in python. </p>
  
  <p>I wanted to set the title of a bokeh figure from outside of the usual figure constructor, but I get a strange error. </p>
  
  <p>Here is the code.</p>
  
  <pre><code>from bokeh.plotting import figure
  p = figure()
  p.title = 'new title'
  </code></pre>
  
  <p>But when I tried this code, I get an error message:</p>
  
  <p><code>ValueError: expected an instance of type Title, got new plot of type str</code></p>
  
  <p>So it seems like I need to create a <code>Title</code> object or something to pass to the figure. However in the bokeh <a href="https://bokeh.pydata.org/en/latest/docs/user_guide/styling.html#Title" rel="noreferrer">documentation</a> there is no mention of how to set the title. There is only mention of how to change the title font or the title color, etc. </p>
  
  <p>Does anyone know how to set the title of the plot from outside of the usual <code>figure(title='new title')</code></p>