code: protected function checkSeparator()
      {
          $line = fgets($this->fileHandle);
          if ($line === false) {
              return;
          }
  
          if ((strlen(trim($line, "\r\n")) == 5) && (stripos($line, 'sep=') === 0)) {
              $this->delimiter = substr($line, 4, 1);
  
              return;
          }
  
          return $this->skipBOM();
      }
docs: Identify any separator that is explicitly set in the file.