It's important to point out that EVERYTHING to do with the MicroPython work on the micro:bit was done by a community of volunteers working in their spare time. Source code here: https://github.com/bbcmicrobit/micropython Documentation here: https://microbit-micropython.readthedocs.io/en/latest/

I estimate around 80 people volunteered time to bring Python and associated tools (such as the browser based editor, command line tools and a native editor called "Mu" https://mu.readthedocs.io/en/latest/) to micro:bit.

At the heart of all this work was the creator of MicroPython, Damien George who volunteered a huge number of hours to bringing a full reimplementation of Python3 (without standard library) to micro:bit. Check it out, it's awesome. MicroPython is both a reimplementation of Python 3 but on the micro:bit also has music, a simple speech synthesiser, funky display functions, radio and a simple file system all built in. :-)