ReachingDefinitionAnalyser(Function<Vertex,Set<Definition>> gen,Function<Vertex,Set<Definition>> kill){
  this.gen=gen;
  this.kill=kill;
}

ReachingDefinitionAnalyser ( Function < Vertex , Set < Definition > > gen , Function < Vertex , Set < Definition > > kill ) { this . gen = gen ; this . kill = kill ; }
creates a new reaching definition analyser .
