code: func IsHeader(packet []byte) bool {
  	return len(packet) > 6 && packet[0]&1 == 1 &&
  		packet[1] == 'v' &&
  		packet[2] == 'o' &&
  		packet[3] == 'r' &&
  		packet[4] == 'b' &&
  		packet[5] == 'i' &&
  		packet[6] == 's'
  }
docs: // IsHeader returns wether the packet is a vorbis header.