trait EquivalentPoint {
// Required methods
fn previous_equivalent_point(&self) -> Option<(DomRoot<Node>, u32)>;
fn next_equivalent_point(&self) -> Option<(DomRoot<Node>, u32)>;
fn first_equivalent_point(self) -> (DomRoot<Node>, u32);
fn last_equivalent_point(self) -> (DomRoot<Node>, u32);
}