pub fn clear(&mut self) {
        self.cells_.clear();
        self.vertices_.clear();
        self.edges_.clear();
    }
/// clear the list of cells, vertices and edges
clear the list of cells, vertices and edges
clear the list of cells vertices and edges
pub fn clear(&mut self) {
        self.cells_.clear();
        self.vertices_.clear();
        self.edges_.clear();
    }
pub fn clear ( & mut self ) { self . cells_ . clear ( ) ; self . vertices_ . clear ( ) ; self . edges_ . clear ( ) ; }
clear the list of cells, vertices and edges
clear the list of cells vertices and edges
&mut self