title: Line plot with arrows in matplotlib
body: <p>I have a line graph that I want to plot using arrows instead of lines. That is, the line between successive pairs of points should be an arrow going from the first point to the second point.</p>
  
  <p>I know of the <code>arrow</code> function, but that only seems to do individual arrows. Before I work out a way to try and use this to do a whole plot, is there a nicer way to do it?</p>