Merge pull request matplotlib#3625 from horvatha/master

animate_decay.py example code is less complicated

Author: pelson

examples/animation/animate_decay.py

@@ -3,14 +3,12 @@
 import matplotlib.animation as animation
 
 
-def data_gen():
-    t = data_gen.t
+def data_gen(t=0):
     cnt = 0
     while cnt < 1000:
         cnt += 1
         t += 0.05
         yield t, np.sin(2*np.pi*t) * np.exp(-t/10.)
-data_gen.t = 0
 
 fig, ax = plt.subplots()
 line, = ax.plot([], [], lw=2)