old_contents: 
  from bokeh.charts import Histogram, defaults, vplot, hplot, show, output_file
  from bokeh.sampledata.autompg import autompg as df
  
  defaults.plot_width = 400
  defaults.plot_height = 350
  
  # input options
  hist  = Histogram(df['mpg'], title="df['mpg']")
  hist2 = Histogram(df, 'displ', title="df, 'displ'")
  hist3 = Histogram(df, values='hp', title="df, values='hp'", density=True)
  
  hist4 = Histogram(df, values='hp', color='cyl',
                    title="df, values='hp', color='cyl'", legend='top_right')
  
  hist5 = Histogram(df, values='mpg', bins=50,
                    title="df, values='mpg', bins=50")
  hist6 = Histogram(df, values='mpg', bins=[10, 20, 30, 40],
                    title="df, values='mpg', bins=[10, 20, 30, 40")
  
  output_file("histogram_multi.html", title="histogram_multi.py example")
  
  show(vplot(
      hplot(hist, hist2),
      hplot(hist3, hist4),
      hplot(hist5, hist6)
  ))
  
new_contents: 
  from bokeh.charts import Histogram, defaults, vplot, hplot, show, output_file
  from bokeh.sampledata.autompg import autompg as df
  
  defaults.plot_width = 400
  defaults.plot_height = 350
  
  # input options
  hist  = Histogram(df['mpg'], title="df['mpg']")
  hist2 = Histogram(df, 'displ', title="df, 'displ'")
  hist3 = Histogram(df, values='hp', title="df, values='hp'", density=True)
  
  hist4 = Histogram(df, values='hp', color='cyl',
                    title="df, values='hp', color='cyl'", legend='top_right')
  
  hist5 = Histogram(df, values='mpg', bins=50,
                    title="df, values='mpg', bins=50")
  hist6 = Histogram(df, values='mpg', bins=[10, 15, 25, 100], tooltips=[('Bin', "@label")],
                    title="df, values='mpg', bins=[10, 15, 25, 100]")
  
  output_file("histogram_multi.html", title="histogram_multi.py example")
  
  show(vplot(
      hplot(hist, hist2),
      hplot(hist3, hist4),
      hplot(hist5, hist6)
  ))
  
subject: change last histogram to use non uniform custom sized bins