title: UFuncTypeError: ufunc 'clip' did not contain a loop with signature matching types (dtype('<U41'), dtype('<U41'), dtype('<U41')) -> dtype('<U41')
body: <p>I have got error when using <code>cv2_imshow</code> from <code>google colab</code>.
  The code I tried is:</p>
  
  <pre><code>from google.colab.patches import cv2_imshow
  def img(path):
      cv2_imshow(path)
  </code></pre>
  
  <p>But this throws the following error:</p>
  
  <blockquote>
    <p>--------------------------------------------------------------------------- UFuncTypeError                            Traceback (most recent call
    last)  in ()
          1 for file in np.hstack((human_files[:3], dog_files[:3])):
    ----> 2     run_app(file)</p>
    
    <p>3 frames /usr/local/lib/python3.6/dist-packages/numpy/core/_methods.py
    in _clip_dep_invoke_with_casting(ufunc, out, casting, *args, **kwargs)
         83     # try to deal with broken casting rules
         84     try:
    ---> 85         return ufunc(*args, out=out, **kwargs)
         86     except _exceptions._UFuncOutputCastingError as e:
         87         # Numpy 1.17.0, 2019-02-24</p>
    
    <p>UFuncTypeError: ufunc 'clip' did not contain a loop with signature
    matching types (dtype('
    dtype('
  </blockquote>
  
  <p>Help!!</p>