code: public static boolean isKnown(byte opcode) {
          return (opcode == CONTINUATION) || (opcode == TEXT) || (opcode == BINARY) || (opcode == CLOSE) || (opcode == PING) || (opcode == PONG);
      }
docs: Test for known opcodes (per the RFC spec)
  
  @param opcode the opcode to test
  @return true if known. false if unknown, undefined, or reserved