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
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
Returns a 'dot' representation of the process. A graph describing
 the tree of flow expressions that compose the process.