title: AttributeError: Unknown property cmap
body: <p>I have the following 2 errors:</p>
  
  <pre><code>AttributeError: Unknown property cmap
  </code></pre>
  
  <p>and </p>
  
  <pre><code>Cannot find reference 'coolwarm' in 'cm.py'
  </code></pre>
  
  <p>I have run:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import matplotlib
  import matplotlib.cm as cm
  </code></pre>
  
  <p>Code I get the error with is </p>
  
  <pre><code>fig = plt.figure()
  ax1 = fig.add_subplot(111)
  ax2 = ax1.twiny()
  
  ax1.plot(result['tme'], result['spread'], ".", markersize=1, 
  c=result['bdaterange'], cmap=cm.coolwarm) 
  </code></pre>