title: Show 2 plots at same time instead of one after another in matplotlib
body: <p>I have the following code which shows a matplotlib plot first. Then, I have to close the first plot so that the second plot appears.</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  import matplotlib.pyplot as plt
  import mglearn
  
  # generate dataset
  X, y = mglearn.datasets.make_forge()
  # plot dataset
  mglearn.discrete_scatter(X[:, 0], X[:, 1], y)
  plt.legend(["Class 0", "Class 1"], loc=4)
  plt.xlabel("First feature")
  plt.ylabel("Second feature")
  print("X.shape: {}".format(X.shape))
  
  plt.show()
  
  X, y = mglearn.datasets.make_wave(n_samples=40)
  plt.plot(X, y, 'o')
  plt.ylim(-3, 3)
  plt.xlabel("Feature")
  plt.ylabel("Target")
  
  plt.show()
  </code></pre>
  
  <p>I would like to have the 2 matplotlib plots appear at the same time. </p>