A Visualization for sets and maps:

	set == ordered items w/o dups
			1
			4
			7
			9

	multiset ==ordered items w/dups
			1
			4
			4
			7
			9

	map == order keys with values w/o dups
			key	value
			1 -- c
			4 -- x
			7 -- j
			9 -- w

	multimap == order keys with values w/dups
			key	value
			1 -- c
			4 -- x
			4 -- d
			7 -- j
			9 -- w