# Is self a upper case letter? (from 'A' to 'Z')
	#
	#     assert 'A'.is_upper   == true
	#     assert 'A'.is_upper   == true
	#     assert 'z'.is_upper   == false
	#     assert '$'.is_upper   == false
	fun is_upper : Bool
	do
		return self >= 'A' and self <= 'Z'
	end