pynucastro 3: A community library for nuclear astrophysics

We describe the latest release of pynucastro: a community python library for nuclear astrophysics. The goal of the pynucastro project is to build the tools needed to interactively explore nuclear properties, reaction rates, and networks, and to export these networks to a variety of simulation codes. Major changes in pynucastro since the last major release include new rate approximations, a stellar equation of state, support for the StarLib library and rate uncertainties, and new tools for exploring networks.