title: Positioning text by axis fraction
body: <p>Is there a way to position text in a figure by the fraction of the axis? I want the text in the same position for all my plots regardless of their differing ranges in x and y. This functionality is in ax.annotate() but I need to put in the extra 'xy' argument which makes my code harder to read. </p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  
  fig = plt.figure() 
  ax = fig.add_subplot(1, 1, 1)
  ax.plot(np.arange(10),12*np.arange(10)) 
  ax.annotate('Correct Position', xy=(0, 0), xytext=(0.4, 0.7), textcoords='axes fraction')
  ax.text(0.4, 0.7, 'Incorrect Position')
  
  plt.show()
  </code></pre>