doc the then env call back on_change_input have an optional reason keyword and…

theano/gof/env.py

@@ -49,7 +49,7 @@ class Env(utils.object2):
         Called whenever a node is pruned (removed) from the env,
         after it is disconnected from the graph.
 
-    - feature.on_change_input(env, node, i, r, new_r)*
+    - feature.on_change_input(env, node, i, r, new_r, [reason=None])*
         Called whenever node.inputs[i] is changed from r to new_r.
         At the moment the callback is done, the change has already
         taken place.

theano/gof/toolbox.py

@@ -186,12 +186,12 @@ class PrintListener(object):
         if self.active:
             print "-- pruning: %s" % node
 
-    def on_change_input(self, env, node, i, r, new_r):
+    def on_change_input(self, env, node, i, r, new_r, reason=None):
         if self.active:
             print "-- changing (%s.inputs[%s]) from %s to %s" % (node, i, r, new_r)
 
 
 class PreserveNames:
-    def on_change_input(self, env, mode, i, r, new_r):
+    def on_change_input(self, env, mode, i, r, new_r, reason=None):
         if r.name is not None and new_r.name is None:
             new_r.name = r.name