use new to create a hash with a default value which is otherwise just nil


months = Hash.new( "month" )
# or like this:
months = Hash.new "month"

1.	Creating Hashes
2.	You can test to see if a hash is empty with empty?
3.	Test how big it is with length or size
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

use new to create a hash with a default value which is otherwise just nil : Hash.new « Hash « Ruby