Removed some unused variables and fixed a formatting error. (#10688)

* Removed some unused variables.

* Fixed the formatting of an error message.

keras/backend/cntk_backend.py

@@ -270,7 +270,7 @@ def placeholder(
         raise ValueError('CNTK backend: creating placeholder with '
                          '%d dimension is not supported, at least '
                          '%d dimensions are needed.'
-                         % (len(cntk_shape, dynamic_axis_num)))
+                         % (len(cntk_shape), dynamic_axis_num))
 
     if name is None:
         name = ''

keras/utils/data_utils.py

@@ -224,7 +224,7 @@ def get_file(fname,
                 raise Exception(error_msg.format(origin, e.errno, e.reason))
             except HTTPError as e:
                 raise Exception(error_msg.format(origin, e.code, e.msg))
-        except (Exception, KeyboardInterrupt) as e:
+        except (Exception, KeyboardInterrupt):
             if os.path.exists(fpath):
                 os.remove(fpath)
             raise

keras/utils/vis_utils.py

@@ -108,7 +108,6 @@ def model_to_dot(model,
             if node_key in model._network_nodes:
                 for inbound_layer in node.inbound_layers:
                     inbound_layer_id = str(id(inbound_layer))
-                    layer_id = str(id(layer))
                     dot.add_edge(pydot.Edge(inbound_layer_id, layer_id))
     return dot