code: func levelToZlib(l CompressionLevel) int {
  	switch l {
  	case DefaultCompression:
  		return zlib.DefaultCompression
  	case NoCompression:
  		return zlib.NoCompression
  	case BestSpeed:
  		return zlib.BestSpeed
  	case BestCompression:
  		return zlib.BestCompression
  	default:
  		return zlib.DefaultCompression
  	}
  }
docs: // This function is required because we want the zero value of
  // Encoder.CompressionLevel to map to zlib.DefaultCompression.