_mask.so : undefined symbol: _Py_ZeroStruct

>git clone https://github.com/cocodataset/cocoapi.git

>cd cocoapi/PythonAPI

>sudo make

*** python 2.7

>python setup.py build_ext install

***python 3.x

>python3 setup.py build_ext install

>cp -r pycocotools <path_to_tensorflow>/models/research/