Reference link updated
# move on to its abstract dependencies (listed in install_requires),
# combining them with its --index option (the PyPi location) and
# turning them into concrete dependencies and installing them.
-# Reference: https://caremad.io/blog/setup-vs-requirement/
+# Reference: https://caremad.io/posts/2013/07/setup-vs-requirement/
--index-url https://pypi.python.org/simple/
-e .
