# File lib/sass/tree/extend_node.rb, line 23
    def cssize(extends, parent)
      @resolved_selector.members.each do |seq|
        if seq.members.size > 1
          raise Sass::SyntaxError.new("Can't extend #{seq.to_a.join}: can't extend nested selectors")
        end

        sseq = seq.members.first
        if !sseq.is_a?(Sass::Selector::SimpleSequence)
          raise Sass::SyntaxError.new("Can't extend #{seq.to_a.join}: invalid selector")
        end

        sel = sseq.members
        parent.resolved_rules.members.each do |seq|
          if !seq.members.last.is_a?(Sass::Selector::SimpleSequence)
            raise Sass::SyntaxError.new("#{seq} can't extend: invalid selector")
          end

          extends[sel] = seq
        end
      end

      []
    end