Better syntax for x,y = first.(xy),last.(xy)

[dlfivefifty]

Right now we can construct the basic monomials via e.g.

P = Zernike()
xy = axes(P,1)
x,y = first.(xy),last.(xy)

which already isn't very nice but even worse if we do 3D do we really want to write:

P = ZernikeBall()
xyz = axes(P,1)
x,y,z = first.(xyz),getindex.(xyz,2),last.(xyz)

The catch: what's a good name???? Best I could come up with is

P = Zernike()
x,y,z = coordinateaxes(P,1)

[MikaelSlevinsky]

What about cartesianaxes? That generalizes: polaraxes, parabolicaxes.

[TSGut]

I was also thinking about options involving "cartesian", so I like cartesianaxes.