#date_time

Symbol as a key in hash would not be clone even the hash is copied

require is the keyword for ruby to use or load the build-in function

strftime is used to formet the date

The Enumerable module can be included in your classes to easily give you the ability to sort, traverse, and search your classes

Usage of IO module

implement in File class 

open a file 

           File.open(“./xxx.txt”, “w+”)

show the content in file

          puts IO.readlines(“xx.txt”)

Struct

Structs are a quick way to bundle attributes together without having to write your own custom class