```
using Polyhedra
using JuMP
using CDDLib
poly = Model()
@variable(poly, -1 <= x <= 1)
@variable(poly, -1 <= y <= 1)
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?