pub fn select_ef(
        &mut self,
        cond: Var<C::N>,
        a: Ext<C::F, C::EF>,
        b: Ext<C::F, C::EF>,
    ) -> Ext<C::F, C::EF> {
        let c = self.uninit();
        self.push_op(DslIr::CircuitSelectE(cond, a, b, c));
        c
    }
Select an extension based on a condition.
crates/recursion/compiler/src/ir/utils.rs