return false if load_and_assign fail to find a model (#919)

return false if load_and_assign fail to find a model

Author: zsdonghao

tensorlayer/files/utils.py

@@ -1711,7 +1711,7 @@ def load_and_assign_npz(sess=None, name=None, network=None):
         raise ValueError("session is None.")
     if not os.path.exists(name):
         logging.error("file {} doesn't exist.".format(name))
-        return
+        return False
     else:
         params = load_npz(name=name)
         assign_params(sess, params, network)
@@ -1766,7 +1766,7 @@ def load_and_assign_npz_dict(name='model.npz', sess=None):
 
     if not os.path.exists(name):
         logging.error("file {} doesn't exist.".format(name))
-        return
+        return False
 
     params = np.load(name)
     if len(params.keys()) != len(set(params.keys())):