# Recursively validate a AST node.
	# This ensure that location and parenting are defined and coherent.
	#
	# After complex low-level AST manipulation and construction,
	# it is recommended to call it.
	#
	# Note: this just instantiate and run an `ASTValidationVisitor`.
	fun validate
	do
		(new ASTValidationVisitor).enter_visit(self)
	end