if (!viewport.to.isEmpty) {
            hooks.push(`${phase}:${viewport.name}.${viewport.to.name}.binding.enter`);
            hooks.push(`${phase}:${viewport.name}.${viewport.to.name}.binding.leave`);
            hooks.push(`${phase}:${viewport.name}.${viewport.to.name}.bound.enter`);
            hooks.push(`${phase}:${viewport.name}.${viewport.to.name}.bound.leave`);