# File lib/sass/selector/comma_sequence.rb, line 100
      def populate_extends(extends, extendee, extend_node = nil, parent_directives = [])
        extendee.members.each do |seq|
          if seq.members.size > 1
            raise Sass::SyntaxError.new("Can't extend #{seq}: 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}: invalid selector")
          elsif sseq.members.any? {|ss| ss.is_a?(Sass::Selector::Parent)}
            raise Sass::SyntaxError.new("Can't extend #{seq}: can't extend parent selectors")
          end

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

            extends[sel] = Sass::Tree::Visitors::Cssize::Extend.new(
              member, sel, extend_node, parent_directives, :not_found)
          end
        end
      end