redef fun accept_reaching_defs(v) do
		super
		v.kill(variable.as(not null))
		v.gen(variable.as(not null), location)
	end

	redef fun accept_reaching_defs(v) do
		super
		v.kill(variable.as(not null))
		v.gen(variable.as(not null), location)
	end

	redef fun accept_reaching_defs(v) do
		super
		v.kill(variable.as(not null))
		v.gen(variable.as(not null), location)
	end

	redef fun accept_reaching_defs(v) do
		# add variables from `for` declaration
		for n_group in n_groups do
			var variables = n_group.variables
			if variables == null then continue
			for variable in variables do v.gen(variable, n_group.location)
		end
		super
		# remove variables from `for` declaration
		for n_group in n_groups do
			var variables = n_group.variables
			if variables == null then continue
			for variable in variables do v.kill(variable)
		end
	end