code: private function parseHeaders($header)
      {
          $headers = [];
          foreach (explode("\r\n", $header) as $line) {
              if (strpos($line, ':') !== false) {
                  list ($key, $value) = explode(': ', $line);
                  $key = str_replace('-', '_', strtolower($key));
                  $headers[$key] = trim($value);
              }
          }
          return $headers;
      }
docs: Get the header info to store.
  
  @param string $header
  
  @return array