text: # line3d.py
  # -------------------------------------------------------------------------
  # Create a three-dimensional parametric plot.
  # ------------------------------------------------------------------------- 
  import numpy as np
  import matplotlib.pyplot as plt
  from mpl_toolkits.mplot3d import Axes3D		# import 3D plotting tool
  
  fig = plt.figure()					# create a new figure
  ax = Axes3D(fig)					# create 3D plotting object attached to figure
  t = np.linspace(0, 5*np.pi, 501)	# define parameter for parametric plot
  
  ax.plot(t * np.cos(t), t * np.sin(t), t)		# generate 3D plot
  plt.show()
  