The `isset` keyword

Property definitions

	# The `isset` keyword
	var n_kwisset: TKwisset is writable, noinit

src/parser/parser_nodes.nit:2772,2--2773,44

	redef fun n_kwisset=(node)
	do
		_n_kwisset = node
		node.parent = self
	end

src/parser/parser_prod.nit:7221,2--7225,4