> so essentially they are getting the shear twice.  That means they are doing 5 interpolations instead of 3. 

I think this amounts to premature optimization.  These functions don't take any significant amount of time compared to the subsequent draw routine that applies the shear and magnification to a whole lot of pixel locations (either in real or fourier space).  

That said, I'm fine with a combined routine that would return both reduced shear and magnification.  Maybe `getLensing`, which would return something that can be directly sent to `applyLensing`:
```
obj.applyLensing(ps.getLensing(pos))
```
And that function could use the utility function you proposed, which would also then be available to users if they wanted it.