The `@` symbol, for at annotations

Property definitions

	# The `@` symbol, for *at* annotations
	var n_at: nullable TAt = null is writable

src/parser/parser_nodes.nit:3061,2--3062,42

	redef fun n_at=(node)
	do
		_n_at = node
		if node != null then node.parent = self
	end

src/parser/parser_prod.nit:8666,2--8670,4