# Return the couple with the lowest value
	#
	# ~~~
	# var c = new Counter[String].from(["a", "a", "b", "b", "b", "c"])
	# assert c.min == "c"
	# ~~~
	#
	# If more than one min exists, the first one is returned.
	fun min: nullable E do
		var min: nullable Int = null
		var elem: nullable E = null
		for e in map.keys do
			var v = map[e]
			if min == null or v < min then
				min = v
				elem = e
			end
		end
		return elem
	end