$ pip install pipenv
$ pipenv --python python3
3.$ pipenv install requests
3.$ pipenv install face_recognition
3.$ pipenv install numpy
3.$ pipenv install opencv-python
**Note : If opencv has error not found version, do following steps :
$ brew install opencv
$ ln -s "$(brew --prefix)"/lib/python3.6/site-packages/cv2*.so "$(pipenv --venv)"/lib/python3.6/site-packages
$ pipenv run python -c "import cv2; print(cv2.__version__)"
$ pipenv shell
$ python