def exchange(base, quot, amount)
      @from_currency = base.upcase.to_sym
      @to_currency = quot.upcase.to_sym

      validate_currency

      base_rate = rates[from_currency].to_f
      quot_rate = rates[to_currency].to_f

      rate = base_rate.zero? ? 0 : (quot_rate / base_rate)
      validate_rate(rate)

      amount * rate
    end
def exchange(base, quot, amount)
      @from_currency = base.upcase.to_sym
      @to_currency = quot.upcase.to_sym

      validate_currency

      base_rate = rates[from_currency].to_f
      quot_rate = rates[to_currency].to_f

      rate = base_rate.zero? ? 0 : (quot_rate / base_rate)
      validate_rate(rate)

      amount * rate
    end
Receive the amount of you desire currency.

 @param [String, String, Numeric] other currency to exchange to.

 @return [amount]

 @example
 currency_converter = CurrencyConverter::Yahoo.new
 currency_converter.exchange('USD', 'EUR', 100)
 currency_converter.exchange('USD', 'INR', 100)