replaced set update to set add.

theano/scan_module/scan_opt.py

@@ -230,12 +230,14 @@ class PushOutNonSeqScan(gof.Optimizer):
 
         max_iterations = 2 * len(local_fgraph_topo) + 3
         counts = 0
-        to_remove_set = set({})
-        to_replace_set = set({})
+        to_remove_set = set()
+        to_remove_add = to_remove_set.add
+        to_replace_set = set()
+        to_replace_add = to_replace_set.add
         to_replace_map = {}
         nto_replace = 0
         def add_to_replace(y, nto_replace):
-            to_replace_set.update([y])
+            to_replace_add(y)
             to_replace_map[y] = nto_replace
             return nto_replace + 1
 
@@ -274,7 +276,7 @@ class PushOutNonSeqScan(gof.Optimizer):
 
                     # We have a candidate node to removable
                     # Step 1. Reconstruct it on outside
-                    to_remove_set.update([nd])
+                    to_remove_add(nd)
                     outside_ins = []
                     for x in nd.inputs:
                         if x in inner_non_seqs_set:
@@ -419,12 +421,15 @@ class PushOutSeqScan(gof.Optimizer):
         max_iterations = 2 * len(local_fgraph_topo) + 3
         counts = 0
 
-        to_remove_set = set({})
-        to_replace_set = set({})
+        to_remove_set = set()
+        to_remove_add = to_remove_set.add
+        to_replace_set = set()
+        to_replace_add = to_replace_set.add
         to_replace_map = {}
         nto_replace = 0
+
         def add_to_replace(y, nto_replace):
-            to_replace_set.update([y])
+            to_replace_add(y)
             to_replace_map[y] = nto_replace
             return nto_replace + 1
 
@@ -440,7 +445,7 @@ class PushOutSeqScan(gof.Optimizer):
         outer_non_seqs = op.outer_non_seqs(node.inputs)
         inner_seqs = op.inner_seqs(clean_inputs)
         inner_seqs_set = set(inner_seqs)
-        inner_seqs_map = dict({v:k for k, v in enumerate(inner_seqs)})
+        inner_seqs_map = dict({v:k for k,v in enumerate(inner_seqs)})
 
         outer_seqs = op.outer_seqs(node.inputs)
         assert len(inner_non_seqs) == len(outer_non_seqs)
@@ -458,7 +463,7 @@ class PushOutSeqScan(gof.Optimizer):
                                (x in inner_seqs_set)
                                for x in nd.inputs]) and
                     not nd in to_remove_set):
-                    to_remove_set.update([nd])
+                    to_remove_add(nd)
                     outside_ins = []
                     depends_on_seqs = False
 
@@ -508,7 +513,7 @@ class PushOutSeqScan(gof.Optimizer):
                       (nd.inputs[0] in inner_seqs_set or
                        nd.inputs[0].owner in to_remove_set) and
                       not nd in to_remove_set):
-                    to_remove_set.update([nd])
+                    to_remove_add(nd)
                     x = nd.inputs[0]
                     if x in inner_seqs_set:
                         outside_ins = outer_seqs[inner_seqs_map[x]]
@@ -996,6 +1001,7 @@ class ScanInplaceOptimizer(Optimizer):
                 info = copy.deepcopy(op.info)
                 if not 'destroy_map' in info:
                     info['destroy_map'] = OrderedDict()
+
                 info['destroy_map'][pos] = [pos + 1 + op.info['n_seqs']]
                 # inputs corresponding to sequences and n_steps
                 ls_begin = node.inputs[:1 + op.n_seqs]