code: function _counter(column, amount, symbol) {
      var amt = parseInt(amount, 10);
      if (isNaN(amt)) {
        amt = 1;
      }
      this._method = 'counter';
      this._single.counter = {
        column: column,
        amount: amt,
        symbol: symbol || '+'
      };
      return this;
    }
docs: ---------------------------------------------------------------------- Helper for the incrementing/decrementing queries.