How to check the dimension names before eliminating some dimensions of a polyhedron?

``` julia
using Polyhedra
using JuMP
using CDDLib

poly = Model()
@variable(poly, -1 <= x <= 1)
@variable(poly, -2 <= y <= 2)
P = polyhedron(poly, CDDLib.Library(:exact))
P_y = eliminate(P, [1])
```

How can I make sure the index `[1]` is corresponding to dimension `x`? Do they always follow the order that they are created in?