def build_request(request_type)
      case request_type
      when :setup_transaction
        SetupTransactionRequest.new(config)
      when :recurrent_transaction
        RecurrentTransactionRequest.new(config)
      when :refund_transaction
        RefundTransactionRequest.new(config)
      when :refund_info
        RefundInfoRequest.new(config)
      when :status
        StatusRequest.new(config)
      when :cancel
        CancelRequest.new(config)
      end
    end
def build_request(request_type)
      case request_type
      when :setup_transaction
        SetupTransactionRequest.new(config)
      when :recurrent_transaction
        RecurrentTransactionRequest.new(config)
      when :refund_transaction
        RefundTransactionRequest.new(config)
      when :refund_info
        RefundInfoRequest.new(config)
      when :status
        StatusRequest.new(config)
      when :cancel
        CancelRequest.new(config)
      end
    end
Factory method for constructing a request.