That would also work.  Do you think that's clearer?
```
wcs = galsim.wcs.readFromFitsHeader(header)
```
vs.
```
wcs = galsim.BaseWCS.readFromFitsHeader(header)
```
I guess I thought the latter was clearer that the return value would be a BaseWCS.  It's a factory function that returns a BaseWCS object.  But I don't have a strong opinion.  The former syntax is also fairly clear, as well as slightly more succinct.