PayPal\Api\Sale::setAmount PHP Method

    public function setAmount($amount)
    {
        $this->amount = $amount;
        return $this;
    }

 public static function createSale()
 {
     $sale = new Sale();
     $sale->setAmount(AmountTest::createAmount());
     $sale->setCreateTime(self::$createTime);
     $sale->setId(self::$id);
     $sale->setParentPayment(self::$parentPayment);
     $sale->setState(self::$state);
     return $sale;
 }