https://github.com/networkx/networkx/commit/eb3a675c5b2b15e33b0a4a35bcee34d6b81ed94d
Replace cb.iterable with np.iterable (#3458)

`matplotlib.cbook.iterable` is deprecated in matplotlib 3.1
https://matplotlib.org/3.1.0/api/cbook_api.html#matplotlib.cbook.iterable

Fixes https://github.com/networkx/networkx/issues/3466

--- networkx/drawing/nx_pylab.py.orig	2019-04-11 14:52:34.000000000 -0600
+++ networkx/drawing/nx_pylab.py	2019-09-11 10:14:12.380878784 -0600
@@ -550,7 +550,6 @@ def draw_networkx_edges(G, pos,
     try:
         import matplotlib
         import matplotlib.pyplot as plt
-        import matplotlib.cbook as cb
         from matplotlib.colors import colorConverter, Colormap, Normalize
         from matplotlib.collections import LineCollection
         from matplotlib.patches import FancyArrowPatch
@@ -576,13 +575,13 @@ def draw_networkx_edges(G, pos,
     # set edge positions
     edge_pos = np.asarray([(pos[e[0]], pos[e[1]]) for e in edgelist])
 
-    if not cb.iterable(width):
+    if not np.iterable(width):
         lw = (width,)
     else:
         lw = width
 
     if not is_string_like(edge_color) \
-            and cb.iterable(edge_color) \
+            and np.iterable(edge_color) \
             and len(edge_color) == len(edge_pos):
         if np.alltrue([is_string_like(c) for c in edge_color]):
             # (should check ALL elements)
@@ -591,7 +590,7 @@ def draw_networkx_edges(G, pos,
                                  for c in edge_color])
         elif np.alltrue([not is_string_like(c) for c in edge_color]):
             # If color specs are given as (rgb) or (rgba) tuples, we're OK
-            if np.alltrue([cb.iterable(c) and len(c) in (3, 4)
+            if np.alltrue([np.iterable(c) and len(c) in (3, 4)
                            for c in edge_color]):
                 edge_colors = tuple(edge_color)
             else:
@@ -673,7 +672,7 @@ def draw_networkx_edges(G, pos,
             line_width = None
             shrink_source = 0  # space from source to tail
             shrink_target = 0  # space from  head to target
-            if cb.iterable(node_size):  # many node sizes
+            if np.iterable(node_size):  # many node sizes
                 src_node, dst_node = edgelist[i][:2]
                 index_node = nodelist.index(dst_node)
                 marker_size = node_size[index_node]
@@ -797,7 +796,6 @@ def draw_networkx_labels(G, pos,
     """
     try:
         import matplotlib.pyplot as plt
-        import matplotlib.cbook as cb
     except ImportError:
         raise ImportError("Matplotlib required for draw()")
     except RuntimeError: