# File lib/parslet/error_reporter/deepest.rb, line 61
      def deepest(cause)
        rank, leaf = deepest_child(cause)
        
        if !deepest_cause || leaf.pos >= deepest_cause.pos
          # This error reaches deeper into the input, save it as reference.
          @deepest_cause = leaf
          return cause
        end
        
        return deepest_cause
      end