# Return all the super modules that defines a value
	# `min_visibility` is used to filter modules by their visibility in `mmodule`.
	fun lookup_all_modules(mmodule: MModule, min_visibility: MVisibility): Sequence[MModule]
	do
		var res = new Array[MModule]
		for m in mmodule.in_importation.greaters do
			if mmodule.visibility_for(m) < min_visibility then continue
			if self.defs.has_key(m) then res.add(m)
		end
		return res
	end