code: public AbstractJobVertex findVertexByID(final JobVertexID id) {
  
  		if (this.inputVertices.containsKey(id)) {
  			return this.inputVertices.get(id);
  		}
  
  		if (this.outputVertices.containsKey(id)) {
  			return this.outputVertices.get(id);
  		}
  
  		if (this.taskVertices.containsKey(id)) {
  			return this.taskVertices.get(id);
  		}
  
  		return null;
  	}
docs: Searches for a vertex with a matching ID and returns it.
  
  @param id
  the ID of the vertex to search for
  @return the vertex with the matching ID or <code>null</code> if no vertex with such ID could be found