[FlopCpp] basic question about constraint from GNU Math Prog to Flopcpp

[marcos.roberto.silva]

Hi all,
I have a model written in GNU MathProg (GLPK) for the
Network Design Problem with the following constraint:

s.t. r1 {i in N, ka in K} : sum{j in N} f[i,j,ka] - sum{l in
N} f[l,i,ka] = (if i==O[ka] then R[ka] else (if i==D[ka]
then -R[ka] else 0));

How can I represent this constraint in Flopcpp?

Thank you.
Best Regards.

Marcos Roberto Silva
Brazil