code: public void show(String what) 
  	{ 
  		if (what.equals("blockers")) showList("blockers",blockerNames); 
  		else if (what.equals("datasets")) showList("datasets", datasetNames); 
  		else if (what.equals("learners")) showList("learners", learnerNames); 
  		else if (what.equals("all")) {
  			show("blockers"); show("datasets"); show("learners"); 
  		} else {
  			System.out.println("usage: show blockers|datasets|learners|all");
  		}
  	}
docs: Show datasets, blockers, or learners.