yotta is a tool that we're building at mbed to make it easier to build better software written in C, C++ or other C-family languages. It's still early in development, so if you have questions/feedback or issues, please report them on Github.
While yotta is written in python, to use it to build software you'll need several non-python dependencies. Detailed installation instructions and links to installers can be found on the yotta docs site.
The best way to get started is to follow the tutorial.
yotta is licensed under Apache-2.0