# Are all letters in `self` upper-case ?
	#
	# ~~~
	# assert "HELLO WORLD".is_upper == true
	# assert "%$&%!".is_upper       == true
	# assert "hello world".is_upper == false
	# assert "Hello World".is_upper == false
	# ~~~
	fun is_upper: Bool
	do
		for i in [0..length[ do
			var char = chars[i]
			if char.is_lower then return false
		end
		return true
	end