# File lib/grape/validations/params_scope.rb, line 71
      def full_name(name, index: nil)
        if nested?
          # Find our containing element's name, and append ours.
          [@parent.full_name(@element), [@index || index, name].map(&method(:brackets))].compact.join
        elsif lateral?
          # Find the name of the element as if it was at the same nesting level
          # as our parent. We need to forward our index upward to achieve this.
          @parent.full_name(name, index: @index)
        else
          # We must be the root scope, so no prefix needed.
          name.to_s
        end
      end