src/DataLoader.php
public function prime($key, $value)
    {
        $this->checkKey($key, __METHOD__);

        $cacheKey = $this->getCacheKeyFromKey($key);

        // Only add the key if it does not already exist.
        if (!$this->promiseCache->has($cacheKey)) {
            // Cache a rejected promise if the value is an Error, in order to match
            // the behavior of load(key).
            $promise = $value instanceof \Exception ? $this->getPromiseAdapter()->createRejected($value) : $this->getPromiseAdapter()->createFulfilled($value);

            $this->promiseCache->set($cacheKey, $promise);
        }

        return $this;
    }
public function prime($key, $value)
    {
        $this->checkKey($key, __METHOD__);

        $cacheKey = $this->getCacheKeyFromKey($key);

        // Only add the key if it does not already exist.
        if (!$this->promiseCache->has($cacheKey)) {
            // Cache a rejected promise if the value is an Error, in order to match
            // the behavior of load(key).
            $promise = $value instanceof \Exception ? $this->getPromiseAdapter()->createRejected($value) : $this->getPromiseAdapter()->createFulfilled($value);

            $this->promiseCache->set($cacheKey, $promise);
        }

        return $this;
    }
{@inheritdoc}