remove useless code

x2paddle/core/graph.py

@@ -100,8 +100,3 @@ class Graph(object):
             raise Exception("node[{}] not in graph".format(dst))
         self.node_map[dst].inputs.append(src)
         self.node_map[src].outputs.append(dst)
-
-    def print(self):
-        for i, tmp in enumerate(self.topo_sort):
-            print(tmp, self.node_map[tmp].layer_type, self.node_map[tmp].inputs,
-                  self.node_map[tmp].outputs)