# File lib/edi4r/diagrams.rb, line 241
    def expand
      each do |node|
        if node.is_a? TNode and node.tail == nil
          #        puts "Expanding #{node}"
          tail = Branch.new(@key, node.name, @root)

          # Merge TNode with first tail node (trigger segment)
          trigger_segment = tail.shift
          node.name = trigger_segment.name
          if trigger_segment.status != 'M' or trigger_segment.maxrep != 1
            raise "#{trigger_segment.name}: Not a trigger seg!" 
          end
          node.tail = tail.expand # Recursion!
        end
      end
      self
    end