code: function each(cursor, callback) {
    let Cursor = loadCursor();
  
    if (!callback) throw MongoError.create({ message: 'callback is mandatory', driver: true });
    if (cursor.isNotified()) return;
    if (cursor.s.state === Cursor.CLOSED || cursor.isDead()) {
      return handleCallback(
        callback,
        MongoError.create({ message: 'Cursor is closed', driver: true })
      );
    }
  
    if (cursor.s.state === Cursor.INIT) cursor.s.state = Cursor.OPEN;
  
    // Define function to avoid global scope escape
    let fn = null;
    // Trampoline all the entries
    if (cursor.bufferedCount() > 0) {
      while ((fn = loop(cursor, callback))) fn(cursor, callback);
      each(cursor, callback);
    } else {
      cursor.next((err, item) => {
        if (err) return handleCallback(callback, err);
        if (item == null) {
          return cursor.close({ skipKillCursors: true }, () => handleCallback(callback, null, null));
        }
  
        if (handleCallback(callback, null, item) === false) return;
        each(cursor, callback);
      });
    }
  }
docs: Iterates over all the documents for this cursor. See Cursor.prototype.each for more information.
  
  @method
  @deprecated
  @param {Cursor} cursor The Cursor instance on which to run.
  @param {Cursor~resultCallback} callback The result callback.