Magics are special instructions to the IPython interpreter that perform specialized actions. There are two types of magics:

We are already familiar with one of the magic command, that is, %pylab inline. This particular magic does two of the following things: it imports NumPy and matplotlib, and sets up the notebook for inline plots. To see one of the other options, change the cell to %pylab.

Run this cell and then run the cell that produces the plot again. Instead of drawing the graph inline, IPython will now open a new window with the plot as shown in the following screenshot:

This window is interactive and you can resize the graph, move it, and save it to a file from here.

Another useful magic is %timeit, which records the time it takes to run a line of Python code. Run the following code in a new cell in the notebook:

%timeit return_on_investment...