# File lib/mofo/xfn.rb, line 57
  def initialize(doc)
    @links = doc.search("a[@rel]").map do |rl| 
      relation = rl[:rel].split(' ') 

      # prune invalid relations
      relation.each { |r| relation.delete(r) unless @@valid_relations.include? r }
      relation = relation.first if relation.size == 1
      next if relation.empty?

      Link.new(:name => rl.innerHTML, :link => rl[:href], :relation => relation)
    end.compact
  end