title: ipython notebook bokeh and output_notebook
body: <p>What is happening when I get the following error? There is no error from within the notebook. But when I do this in regular iPython I'm wondering what is happening.... and what <code>In:</code> means... see error below.... (last 5 lines)</p>
  
  <pre><code>#set up domain and function with max
  x = np.linspace(lower, upper, steps)
  y = func(x)
  y_max = np.amax(y) * 1.1
  
  output_notebook()
  
  p = figure(
     tools="pan,box_zoom,reset,save",
     y_range=[0, y_max], title="Some Beta Distributions",
     x_axis_label='days', y_axis_label='value'
  )
  
  p.line(x, y, legend = "pdf", line_color="blue")
  
  show(p)
  /usr/local/lib/python2.7/dist-packages/IPython/utils/path.py:303: UserWarning: IPython dir
   '/home/vagrant/.ipython' is not a writable location, using a temp directory.
    " using a temp directory.".format(ipdir))
  In :
  In :
  </code></pre>