%matplotlib inline
from pylab import *
import matplotlib.animation
import matplotlib.patches

fig, ax = plt.subplots(figsize=(13, 8))
def update(frame):  
    ax.add_patch(matplotlib.patches.Rectangle(numpy.array([0, 0]), 1, 1))
anim = matplotlib.animation.FuncAnimation(fig, update, frames=10, blit=True)  # blit=True !!
anim.save('anim.mp4', fps=20, writer='avconv', codec='libx264')

python3.5/site-packages/matplotlib/animation.py in _draw_frame(self, framedata)
   1212         self._drawn_artists = self._func(framedata, *self._args)
   1213         if self._blit:
-> 1214             for a in self._drawn_artists:
   1215                 a.set_animated(self._blit)

TypeError: 'NoneType' object is not iterable