code: function wrap(value) {
      var raw;
      if (typeof value === 'function') {
        return this.outputQuery(this.compileCallback(value), true);
      }
      raw = this.unwrapRaw(value);
      if (raw) {
        return raw;
      }
      if (typeof value === 'number') {
        return value;
      }
      return this._wrapString(value + '');
    }
docs: Puts the appropriate wrapper around a value depending on the database engine, unless it's a knex.raw value, in which case it's left alone.