code: protected function contraAccountNumber(array $lines)
      {
          if (!isset($lines[1])) {
              return null;
          }
  
          if (preg_match('/^([0-9.]{11,14}) /', $lines[1], $match)) {
              return str_replace('.', '', $match[1]);
          }
  
          if (preg_match('/^GIRO([0-9 ]{9}) /', $lines[1], $match)) {
              return trim($match[1]);
          }
  
          return null;
      }
docs: Get the contra account from a transaction
  
  @param array $lines The transaction text at offset 0 and the description at offset 1
  @return string|null