src/Client/CurlHttpClient.php
public function send(RequestInterface $request)
    {
        $deferred = new Deferred();
        try {
            $response = $this->call($request);
            $deferred->resolve($response);
        } catch (\Exception $caught) {
            $deferred->reject($caught);
        }

        return $deferred->promise();
    }
public function send(RequestInterface $request)
    {
        $deferred = new Deferred();
        try {
            $response = $this->call($request);
            $deferred->resolve($response);
        } catch (\Exception $caught) {
            $deferred->reject($caught);
        }

        return $deferred->promise();
    }
Send out an HTTP requests returning a promise

@param RequestInterface $request

@return PromiseInterface