title: how to test if a variable is pd.NaT?
body: <p>I'm trying to test if one of my variables is pd.NaT. I know it is NaT, and still it won't pass the test. As an example, the following code prints nothing :</p>
  
  <pre><code>a=pd.NaT
  
  if a == pd.NaT:
      print("a not NaT")
  </code></pre>
  
  <p>Does anyone have a clue ? Is there a way to effectively test if <code>a</code> is NaT?</p>