Backport PR matplotlib#12501: Rectified plot error (matplotlib#12541)

Author: meeseeksmachine

.flake8

@@ -103,7 +103,7 @@ per-file-ignores =
     tutorials/introductory/images.py: E402, E501
     tutorials/introductory/pyplot.py: E402, E501
     tutorials/introductory/sample_plots.py: E501
-    tutorials/introductory/usage.py: E402, E501
+    tutorials/introductory/usage.py: E501
     tutorials/text/annotations.py: E501
     tutorials/text/pgf.py: E501
     tutorials/text/text_intro.py: E402

tutorials/introductory/usage.py

@@ -600,18 +600,18 @@ def my_plotter(ax, data1, data2, param_dict):
 # Prior to version 1.0, show() generally could not be called
 # more than once in a single script (although sometimes one
 # could get away with it); for version 1.0.1 and above, this
-# restriction is lifted, so one can write a script like this:
-
-import numpy as np
-import matplotlib.pyplot as plt
-
-plt.ioff()
-for i in range(3):
-    plt.plot(np.random.rand(10))
-    plt.show()
-
-###############################################################################
-# which makes three plots, one at a time.
+# restriction is lifted, so one can write a script like this::
+#
+#     import numpy as np
+#     import matplotlib.pyplot as plt
+#
+#     plt.ioff()
+#     for i in range(3):
+#         plt.plot(np.random.rand(10))
+#         plt.show()
+#
+# which makes three plots, one at a time. I.e. the second plot will show up,
+# once the first plot is closed.
 #
 # Summary
 # -------