text: """
  tanh
  ~~~~
  
  Plots a graph of the tanh function."""
  
  import numpy as np
  import matplotlib.pyplot as plt
  
  z = np.arange(-5, 5, .1)
  t = np.tanh(z)
  
  fig = plt.figure()
  ax = fig.add_subplot(111)
  ax.plot(z, t)
  ax.set_ylim([-1.0, 1.0])
  ax.set_xlim([-5, 5])
  ax.grid(True)
  ax.set_xlabel('z')
  ax.set_title('tanh function')
  
  plt.show()
  