I want to draw a plot with matplotlib with axis on both sides of the plot, similar to this plot (the color is irrelevant to this question):

How can I do this with matplotlib?
Note: contrary to what is shown in the example graph, I want the two axis to be exactly the same, and want to show only one graph. Adding the two axis is only to make reading the graph easier.
There are a couple of relevant examples in the online documentation: