title: pandas data frame read_excel: How to look for empty cells?
body: <p>I have a data frame that is constructed by pd.read_excel.
  I want to create a second data frame by selecting all rows of the prior data frame where a column of the excel has a empty cell.</p>
  
  <p>Something like </p>
  
  <pre><code>A = df.loc[df["column"]==None]
  </code></pre>
  
  <p>did not work.</p>