title: AttributeError: 'NoneType' object has no attribute 'scatter'
body: <p>I have been trying working with matplotlib and suddenly it stopped working. Whenever I call:</p>
  <pre><code>import matplotlib.pyplot as plt
  fig = plt.figure()
  ax = fig.add_subplot(projection = '3d')
  
  ax.scatter(fb_df['r'], fb_df['g'], fb_df['b'])
  
  plt.show()
  </code></pre>
  <p>I have the following error returned:</p>
  <pre><code>---------------------------------------------------------------------------
  AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-11-7d1c064ffc44&gt; in &lt;module&gt;
        3 ax = fig.add_subplot(projection = '3d')
        4 
  ----&gt; 5 ax.scatter(fb_df['r'], fb_df['g'], fb_df['b'])
        6 #ax.set_xlabel('R')
        7 #ax.set_ylabel('G')
  
  AttributeError: 'NoneType' object has no attribute 'scatter'
  </code></pre>
  <p>I am going crazy because it makes no sense to me. I tried uninstalling and reinstalling matplotlib, I also tried closing and reopening jupyter notebooks.</p>