function post($url, $post){
  $context = array();
  if (is_array($post)){
    ksort($post);
    $context['http'] = array(
      'method' => 'POST',
      'content' => http_build_query($post, '', '&')
    );
  }
  else{
    $context['http'] = array(
      'method' => 'POST',
      'content' => $post
    );
  }
  return @file_get_contents($url, false, stream_context_create($context));
}