title: cURL library is not loaded google app engine
body: <p>I'm trying to build a simple PHP web page on google app engine.
  I'm getting the following error on loading page!</p>
  
  <p><strong>cURL library is not loaded</strong></p>
  
  <p>I've also read on google app engine documentation page that cURL extension is pre-installed and enabled on system...! 
  <a href="https://cloud.google.com/appengine/docs/flexible/php/runtime" rel="nofollow noreferrer">Here</a></p>
  
  <p>here is my code</p>
  
  <pre><code>    &lt;?php
  require __DIR__ . '/vendor/autoload.php';
  
  try {
      $api = new \Kavenegar\KavenegarApi("6C5846314B3***********62644E6A49663031307967442F565256634958373754593D");
      $sender = "10004346";
      $message = "Test message!";
      $receptor = array("0901***6780");
      $result = $api-&gt;Send($sender, $receptor, $message);
      if ($result) {
          foreach ($result as $r) {
              echo "messageid = $r-&gt;messageid";
              echo "message = $r-&gt;message";
              echo "status = $r-&gt;status";
              echo "statustext = $r-&gt;statustext";
              echo "sender = $r-&gt;sender";
              echo "receptor = $r-&gt;receptor";
              echo "date = $r-&gt;date";
              echo "cost = $r-&gt;cost";
          }
      }
  }
  catch(\Kavenegar\Exceptions\ApiException $e) {
  
      echo $e-&gt;errorMessage();
  }
  catch(\Kavenegar\Exceptions\HttpException $e) {
      echo $e-&gt;errorMessage();
  }
  </code></pre>
  
  <p>how can I fix this?</p>