def expiring?(number_of_months=3)
      (Date.parse(expiration_date) - number_of_months.months) <= Date.today.at_beginning_of_month
    end
def expiring?(number_of_months=3)
      (Date.parse(expiration_date) - number_of_months.months) <= Date.today.at_beginning_of_month
    end
Checks if this customer's card will expire within the next :months.

 number_of_months -> Number of months within this card will expire. Defaults to 3