redef fun above_threshold do
		var above = new HashSet[ELM]
		var threshold = threshold
		for element, value in values do
			if value.to_f > threshold then above.add(element)
		end
		return above
	end

	redef fun above_threshold do
		var above = new HashSet[ELM]
		var threshold = threshold
		for element, value in values do
			if value > threshold then above.add(element)
		end
		return above
	end