omar_rules.rb

$ irb
>> omar = ["a", "b", "c"]
=> ["a", "b", "c"]
>> omar.to_s
=> "abc"
>> class Array
>>   def to_s
>>     output = "I am an Array.  I contain: "
>>     self.each {|x| output += " element: #{x} " }
>>     return output
>>   end
>> end
=> nil
>> omar.to_s
=> "I am an Array.  I contain:  element: a  element: b  element: c "
>>