title: Showing histogram code never ends
body: <p>I created and ran a very simple python code to show a histogram. The histogram shows successfully but the program never finishes. Could you please help?</p>
  
  <p>By clicking Ctrl and C, the following message shows up.</p>
  
  <pre><code>File "hist_ex.py", line 9, in &lt;module&gt;
  plt.show()
  File "/Users/myusername/.pyenv/versions/anaconda3-4.4.0/lib/python3.6/site-packages/matplotlib/pyplot.py", line 254, in show
  return _show(*args, **kw)
  File "/Users/myusername/.pyenv/versions/anaconda3-4.4.0/lib/python3.6/site-packages/matplotlib/backend_bases.py", line 218, in show
  cls.mainloop()
  File "/Users/myusername/.pyenv/versions/anaconda3-4.4.0/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 1078, in mainloop
  Tk.mainloop()
  File "/Users/myusername/.pyenv/versions/anaconda3-4.4.0/lib/python3.6/tkinter/__init__.py", line 557, in mainloop
  _default_root.tk.mainloop(n)
  KeyboardInterrupt
  </code></pre>
  
  <p>And here is my python code.</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  
  x = np.random.normal(50, 10, 1000)
  
  plt.hist(x)
  plt.show()
  </code></pre>