instance method symbol_unscoping

# File activerecord/lib/active_record/relation/query_methods.rb, line 880
    def symbol_unscoping(scope)
      if !VALID_UNSCOPING_VALUES.include?(scope)
        raise ArgumentError, "Called unscope() with invalid unscoping argument ':#{scope}'. Valid arguments are :#{VALID_UNSCOPING_VALUES.to_a.join(", :")}."
      end

      single_val_method = Relation::SINGLE_VALUE_METHODS.include?(scope)
      unscope_code = "#{scope}_value#{'s' unless single_val_method}="

      case scope
      when :order
        self.reverse_order_value = false
        result = []
      else
        result = [] unless single_val_method
      end

      self.send(unscope_code, result)
    end