transform, using a vector. Or something like that!
transform_var = vector_arg * [size/2, size/2, size/2]
vector_argin the default case, would be something like
[0, -1, 0]
But it doesn't seem like OpenSCAD supports this higher level use of arrays/vectors - and I don't want to loop through them when there's probably a simpler way to do it.
For my earlier use, I wanted a rotation - so I just went with passing in rotation as degrees but that was a bit unelegant. I guess there should be some source that shows a similar use for built-in modules that take a vector.