gistfile1.txt

var useExt = false

const [line, addLine]

const processCommand = (rawCommand) => {
  var arg;
  var command;
  const i = rawCommand.indexOf(' ');
  if (i != -1 && rawCommand.length() != i + 1) {
    arg = rawCommand.substring(i + 1).trim();
    command = rawCommand.substring(0, i);
  } else {
    arg = "";
    command = rawCommand;
  }

  switch (command) {
    case "clearTerminal":
      setLines([]);
      break;
  }
}

const onPrint = (s) => {
  if ("#!useExt".equals(s.trim())) {
    useExt = true;
    return;
  }

  if (useExt && s.startsWith("#!")) {
    this.processCommand(s.substring(2));
  } else {
    addLine(s);
  }
}