SymPy function with 2 variables

i am trying:

julia> a=Equality(x^2 + y^3, 31)

i would like to get x=2 and y=3. How ca i do it?

I tried solve(a,[x,y]) and solve(a) but i am getting:
(-sqrt(31 - y^3), y)
(sqrt(31 - y^3), y)

Please, read PSA: make it easier to help you, especially, points 1 and 3.

From the documentation you should use solveset, no?

i tried solveset(a,[x,y]) and it returns ∅

I think that you should read this section of the documentation of Sympy: Diophantine, about diophantine equations.

yeah, problem is cubics are not implemented for diophantines yet. So i am looking for any package able to handle this. I can easily do it in Matlab but I really need a solution using Julia.