title: delete duplicate elements whose type is "object" from a numpy array in Python
body: <p>Someone knows how to delete duplicate elements from a numpy array whose data type is object ?</p>
  <p>For instance,</p>
  <pre><code>example=array([[
      array([['first', array([[1, 2, 3]]), 1]], dtype=object),
      array([['second', array([[4, 5, 6]]), 2]], dtype=object),
      array([['first', array([[1, 2, 3]]), 1]], dtype=object)]],
    dtype=object)
  </code></pre>