operators overloading question?

class Whatever
    attr_accessor :number, :str
    def initialize(number)
        @number = number
        @str = "Your number is : ( #{@number} )"   
    end   
end

def >>a  # I wanted to use this operator in order to put an object of class whatever
    puts a.str
end
object = Whatever.new(10)
>>object                # why doesn't it work?