title: Add margin when plots run against the edge of the graph
body: <p>Often when I plot in matplotlib, I get graphs like this:</p>
  
  <p><img src="https://i.stack.imgur.com/ihWom.png" alt="frequency response running along top edge"></p>
  
  <p>You can't see the function because it runs against the edge of the plot.</p>
  
  <p>Is there any way to <em>automatically</em> add some margin in these cases, so that they look like this:</p>
  
  <p><img src="https://i.stack.imgur.com/CHVKs.png" alt="frequency response with tiny amount of noise"></p>