title: numpy where command on arrays with dtype=object
body: <p>I'm trying to understand the following:</p>
  
  <pre><code>import numpy as np
  foo = np.array([np.array([0, 2, 3]), np.array([0, 2, 3]), np.array([4, 4]), 4], dtype=object)
  np.where(foo == 4)
  </code></pre>
  
  <p>returns an empty list <code>(array([], dtype=int64),)</code>.  But I can clearly see that the 4th element is 4:</p>
  
  <pre><code>foo[3] == 4
  True
  </code></pre>
  
  <p>So how can I find the indices for elements in foo that equal some value without having to loop through it?</p>