Upload a screenshot of a failed Behat step to Imgur

SomethingContext.php

<?php

/**
 * @AfterStep
 */
public function takeScreenshotAfterFailedStep($event)
{
    if ($event->getTestResult()->getResultCode() === \Behat\Testwork\Tester\Result\TestResult::FAILED) {
		$driver = $this->getSession()->getDriver();
		if ($driver instanceof \Behat\Mink\Driver\Selenium2Driver) {
			$stepText = $event->getStep()->getText();
			$imageTitle = preg_replace('#[^a-zA-Z0-9\._-]#', '', $stepText);
			$screenshotUri = $this->uploadScreenshot($imageTitle, $driver->getScreenshot());
			print "Screenshot for '{$stepText}' uploaded to $screenshotUri";
		}
	}
}

/**
 * Upload a screenshot to Imgur
 * @param string $title
 * @param string $imageData
 */
private function uploadScreenshot($title, $imageData)
{
	$curl = curl_init();
		curl_setopt_array($curl, array(
		CURLOPT_URL => "https://api.imgur.com/3/image",
		CURLOPT_RETURNTRANSFER => true,
		CURLOPT_ENCODING => "",
		CURLOPT_MAXREDIRS => 10,
		CURLOPT_TIMEOUT => 30,
		CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
		CURLOPT_CUSTOMREQUEST => "POST",
		CURLOPT_POSTFIELDS => "image=".urlencode(base64_encode($imageData))."&title=$title",
		CURLOPT_HTTPHEADER => array(
			"authorization: Client-ID yourclientidgoeshere",
			"cache-control: no-cache",
			"content-type: application/x-www-form-urlencoded"
		),
	));
	
	$response = curl_exec($curl);
	$error = curl_error($curl);
	curl_close($curl);
	
	$payload = json_decode($response);
	if ($error || property_exists($payload, 'error')) {
		return;
	}
	return $payload->data->link;
}

where to get client id ?