code: function whereBetween(column, values) {
      assert(Array.isArray(values), 'The second argument to whereBetween must be an array.');
      assert(values.length === 2, 'You must specify 2 values for the whereBetween clause');
      this._statements.push({
        grouping: 'where',
        type: 'whereBetween',
        column: column,
        value: values,
        not: this._not(),
        bool: this._bool()
      });
      return this;
    }
docs: Adds a `where between` clause to the query.