curl_setopt_array($curl, array(
CURLOPT_URL => 'https://<domain>/<api prefix>/<version>/update/lead/',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_FOLLOWLOCATION => true,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_POSTFIELDS => array('first_name' => '<first_name>','last_name' => '<last_name>','email' => '<email>','status' => '<status>','source' => '<source>','phone' => '<phone>','location' => '<location>','message' => '<message>','slug' => '<lead_slug>','assignee' => '<assignee_username>'),
CURLOPT_HTTPHEADER => array(
'Authorization: Bearer <access token>'
$response = curl_exec($curl);