Add extra dependency

setup.py

@@ -23,6 +23,9 @@ setup(name='torchy_baselines',
             'sphinx',
             'sphinx-autobuild',
             'sphinx-rtd-theme'
+        ],
+        'render': [
+            'opencv-python'
         ]
       },
       description='Pytorch version of Stable Baselines, implementations of reinforcement learning algorithms.',

torchy_baselines/common/save_util.py

@@ -131,4 +131,4 @@ def json_to_data(json_string, custom_objects=None):
         else:
             # Read as it is
             return_data[data_key] = data_item
-    return return_data
+    return return_data