def actual_value(node, multi_keys)
      multi_keys.inject(node) { |n, key|
        if n
          key == :source ? n.send(key) : n.send(key)
        end
      }
    end
def actual_value(node, multi_keys)
      multi_keys.inject(node) { |n, key|
        if n
          key == :source ? n.send(key) : n.send(key)
        end
      }
    end
Get actual value from the node.

 @param node [Parser::AST::Node]
 @param multi_keys [Array<Symbol>]
 @return [Object] actual value.