Requires stdpopsim, msprime, and demes.
Models for a given species (e.g., humans) can be constructed by
python convert_models.py HomSap
All implemented models from stdpopsim are then stored in demes format in
./catalog/HomSap/
We can run this script on all species in the catalog within python (this is a bit ugly):
import stdpopsim
import os
for species in stdpopsim.species.all_species():
    os.system(f"python convert_models.py {species.id}")