Comparable module in Ruby

Comparable.rb

#to use this module the class has to mixin it and define <=> method

class Bid
  
  include Comparable
  attr_accessor :estimate
  
  def <=>(other_bid)
    if self.estimate > other_bid.estimate
      1
    else if self.estimate < other_bid.estimate 
      -1
    else  
      0
  end
  
end