I'm a core contributor to the Computer Algebra System, SymPy 1 and I've mentored Google Summer of Code students for year 2015 and 2016. I myself was a student in year 2014.
I was intern at Continuum Analytics where automated the process of building noarch conda packages from Python Packaging Index (PyPI). Conda is the package manager which powers the popular python distribution Anaconda 2. I also added support for numpy.median in Numba3, Numba runs your numerical code on LLVM to make it super fast.
I'm also the co developer for the Wikipedia Human Gender Indicators (WHGI) project 4 it is a Wikimedia sponsored project which aims to develop statistical and quantitative indicators for gender gap and raise awareness by observing the trend of gender in biography articles. The website is build using the static website builder Nikola and uses bokeh for visualizations.
I've been involved with various other smallish project using python, you can have a look at my github profile for details 5.