You can test to see if a hash is empty with empty?

months = Hash.new
months.empty? # => true

1.	Creating Hashes
2.	Test how big it is with length or size
3.	use new to create a hash with a default value which is otherwise just nil
4.	access any key in a hash that has a default value
5.	Hash with =>
6.	Hash.new with block logic
7.	This lazily initialized hash maps integers to their factorials

You can test to see if a hash is empty with empty? : Hash.new « Hash « Ruby