Function touchCell

ses.cjs:1268–1278

(key)

  const head=  makeSelfCell(undefined);

  const touchCell=  (key)=>{
    const cell=  keyToCell.get(key);
    if( cell===  undefined||  cell.data===  undefined) {
      // Either the key was GCed, or the cell was condemned.
      return undefined;
     }
    // Becomes most recently used
    spliceOut(cell);
    spliceAfter(head, cell);
    return cell;
   };

  /**
   * @param {K} key