code: public function session($sourceId, $sessionHash, $remoteIp, $userAgent, $userId = null)
      {
          $parameters = [
              'query' => [],
              'body' => json_encode(['sourceId' => $sourceId, 'sessionHash' => $sessionHash, 'remoteIp' => $remoteIp, 'userAgent' => $userAgent, 'userId' => $userId], JSON_UNESCAPED_UNICODE),
              'headers' => [],
          ];
  
          $result = $this->post('v1/events/session', $parameters);
  
          return $result;
      }
docs: Creates a sessionId.
  
  SessionId must be sent along with all subsequent requests to track events.
  
  @param int    $sourceId    the source we should log things on
  @param string $sessionHash Some sort of identifier for the user
  @param string $remoteIp    Ip-address of the user
  @param string $userAgent   the User Agent of the user
  @param int    $userId      Optional override value for the user id