# File lib/ruote/engine/process_status.rb, line 192
    def to_dot (opts={})

      s = [ "digraph \"process wfid #{wfid}\" {" ]
      @expressions.each { |e| s.push(*e.send(:to_dot, opts)) }
      @errors.each { |e| s.push(*e.send(:to_dot, opts)) }
      s << "}"

      s.join("\n")
    end