The expression used as the condition of the `if`

Property definitions

	# The expression used as the condition of the `if`
	var n_expr: AExpr is writable, noinit

src/parser/parser_nodes.nit:1964,2--1965,38

	redef fun n_expr=(node)
	do
		_n_expr = node
		node.parent = self
	end

src/parser/parser_prod.nit:3075,2--3079,4