docs: function Cell(cell) {
          // Adds property: className and content.
          Entity.call(this, cell);
  
          /**
           * ### Cell.x
           *
           * The row number
           */
          this.x = 'undefined' !== typeof cell.x ? cell.x : null;
  
          /**
           * ### Cell.y
           *
           * The column number
           */
          this.y = 'undefined' !== typeof cell.y ? cell.y : null;
  
          /**
           * ### Cell.tdElement
           *
           * Reference to the TD/TH element, if built already
           */
          this.HTMLElement = cell.HTMLElement || null;
      }