pub fn alloc_v(&mut self, constraints: &mut Vec<Constraint>, value: C::N) -> String {
        let tmp_id = self.alloc_id();
        constraints.push(Constraint {
            opcode: ConstraintOpcode::ImmV,
            args: vec![vec![tmp_id.clone()], vec![value.as_canonical_biguint().to_string()]],
        });
        tmp_id
    }
Allocates a variable in the constraint system.
crates/recursion/compiler/src/constraints/mod.rs