We will eventually want an mms.cotrans() routine (perhaps after DMPA to GSE is implemented?) to go from MMS-specific coordinates to geophysical coordinates in a single step.
The only coordinate system supported by pyspedas.cotrans() and not mms.cotrans() is "mag". gse, sm, geo, etc. are already available directly in mms.cotrans().
We will eventually want an mms.cotrans() routine (perhaps after DMPA to GSE is implemented?) to go from MMS-specific coordinates to geophysical coordinates in a single step.