pub fn edge_rot_prev(&self, edge_id: Option<EdgeIndex>) -> Option<EdgeIndex> {
        let _ = edge_id?;
        let twin = self.edge_get_twin_(edge_id);
        self._edge_get_next(twin)
    }
/// Returns a pointer to the rotation previous edge
/// over the starting point of the half-edge.
Returns a pointer to the rotation previous edge
over the starting point of the half-edge.
Returns a pointer to the rotation previous edge over the starting point of the half - edge .
pub fn edge_rot_prev(&self, edge_id: Option<EdgeIndex>) -> Option<EdgeIndex> {
        let _ = edge_id?;
        let twin = self.edge_get_twin_(edge_id);
        self._edge_get_next(twin)
    }
pub fn edge_rot_prev ( & self , edge_id : Option < EdgeIndex > ) -> Option < EdgeIndex > { let _ = edge_id ? ; let twin = self . edge_get_twin_ ( edge_id ) ; self . _edge_get_next ( twin ) }
Returns a pointer to the rotation previous edge
over the starting point of the half-edge.
Returns a pointer to the rotation previous edge over the starting point of the half - edge .
&self
edge_id
Option<EdgeIndex>