title: Error: 'float' object has no attribute 'isna'"
body: <p>I have the below series:</p>
  
  <pre><code>my_series = pd.Series([np.nan, np.nan, ['A', 'B']])
  </code></pre>
  
  <p>I have to loop through my_series and evaluate whether the value is NaN or not and then do something (actions defined as 'do A' and 'do B' for the sake of simplicity).</p>
  
  <p><strong>1st try:</strong></p>
  
  <pre><code>for element in my_series:
      if element.isna():
          print('do A')
      else:
          print('do B')
  </code></pre>
  
  <p>When running it, I've got the error: <em>"'float' object has no attribute 'isna'"</em></p>
  
  <p><strong>2nd try</strong> from the question: <a href="https://stackoverflow.com/questions/44877663/error-float-object-has-no-attribute-notnull">Error: float object has no attribute notnull</a></p>
  
  <pre><code>for element in my_series:
      np.where(element.isnull(), 'do A', 'do B')
  </code></pre>
  
  <p>When running it, I've got the error:  "<em>AttributeError: 'float' object has no attribute 'isnull'</em>"</p>
  
  <p>I haven't found any other similar question here at StackOverflow, I don't know what else to try. </p>