title: Python histogram outline
body: <p>I have plotted a histogram in Jupyter (Python 2) and was expecting to see the outlines of my bars but this is not the case. </p>
  
  <p><a href="https://i.stack.imgur.com/r97fv.png" rel="noreferrer"><img src="https://i.stack.imgur.com/r97fv.png" alt="enter image description here"></a></p>
  
  <p>I'm using the following code:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  from numpy.random import normal
  gaussian_numbers = normal(size=1000)
  plt.hist(gaussian_numbers)
  plt.title("Gaussian Histogram")
  plt.xlabel("Value")
  plt.ylabel("Frequency")
  plt.show()
  </code></pre>