# File lib/rgl/rdot.rb, line 309
309:     def to_s (t = '')
310:       t + "#{@from} #{edge_link} #{to} [\n" +
311:           @options.to_a.collect{ |i|
312:             i[1] && i[0] != 'label' ? 
313:               t + $tab + "#{i[0]} = #{i[1]}" : 
314:               i[1] ? t + $tab + "#{i[0]} = \"#{i[1]}\"" : nil
315:           }.compact.join( "\n" ) + "\n" + t + "]\n"
316:     end