WorkerFactory.php
public function createWorkerPoolWithExpression($implementationExpression, $workerCount = null)
    {
        return WorkerPool::withExpression($this->bootstrapProfile, $implementationExpression, $workerCount);
    }
public function createWorkerPoolWithExpression($implementationExpression, $workerCount = null)
    {
        return WorkerPool::withExpression($this->bootstrapProfile, $implementationExpression, $workerCount);
    }
@param string   $implementationExpression
@param int|null $workerCount

@throws Exception\InvalidArgumentException
@throws Exception\RuntimeException

@return WorkerPool