Grab miniconda3, install mamba in the base environment:
conda install -c conda-forge mamba
then create the bgcval environment and activate it:
mamba env create -n bgcval -f environment.yml
conda activate bgcval
then install the development dependencies:
pip install -e .[develop]
Install 2to3:
pip install 2to3
Usage: use the 3.9 extension and write to disk option:
2to3-3.9 script.py -w
Remove the backup .py.bak files or stash them.