  TauREx 3 is the next generation of the TauREx exoplanet atmospheric retrieval
framework for Windows, Mac, and Linux. It is a complete rewrite with a full
Python stack that makes it easy-to-use, high-performance, dynamic, and
flexible. The new main TauREx program is built with modularity in mind,
allowing the user to augment its functionalities with custom code and
efficiently perform retrievals on custom parameters. We achieve this result by
dynamic determination of fitting parameters, whereby TauREx 3 can detect new
parameters for retrieval from user code through a simple interface. TauREx 3
can act as a library with a simple 'import taurex' command, providing a rich
set of classes and functions related to atmospheric modelling. A 10x speedup in
forward model computations is achieved as compared to the previous version with
a sixfold reduction in retrieval times while maintaining robust results. TauREx
3 is intended as a standalone, all-in-one package for retrievals while the
TauREx 3 Python library can build or augment a user's custom data pipeline
easily.
