Visit a list of arguments ANode with optional parentheses

Property definitions

nitc $ PrettyPrinterVisitor :: visit_args
	# Visit a list of arguments `ANode` with optional parentheses
	fun visit_args(n: nullable ANodes[ANode]) do
		if n == null or n.is_empty then return
		if current_token isa TOpar then
			consume "("
		else
			adds
		end

		visit_list n
		if current_token isa TCpar then consume ")"
	end
src/pretty.nit:102,2--113,4