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