# File lib/jmespath/nodes/subexpression.rb, line 48
      def optimize
        children = @children.map(&:optimize)
        index = 0
        while index < children.size - 1
          if children[index].chains_with?(children[index + 1])
            children[index] = children[index].chain(children[index + 1])
            children.delete_at(index + 1)
          else
            index += 1
          end
        end
        Chain.new(children)
      end