function Set.intersection(c,m)local V={}for c,R in pairs(c)do if m[c]~=nil then V[c]=true end end return V end

function Set.intersection(set, otherSet)
	local newSet = {}
	for key, _ in pairs(set) do
		if otherSet[key] ~= nil then
			newSet[key] = true
		end
	end
	return newSet
end
