String doString() {
		interp.getToken();
		if (interp.token!='.')
			interp.error("'.' expected");
		interp.getToken();
		if (interp.token!=WORD)
			interp.error("Function name expected: ");
		String name = interp.tokenString;
		if (name.equals("append"))
			return appendToBuffer();
		else if (name.equals("copy"))
			return copyStringToClipboard();
		else if (name.equals("copyResults"))
			return copyResults();
		else if (name.equals("getResultsHeadings"))
			return getResultsHeadings();
		else if (name.equals("paste"))
			return getClipboardContents();
		else if (name.equals("resetBuffer"))
			return resetBuffer();
		else if (name.equals("buffer"))
			return getBuffer();
		else
			interp.error("Unrecognized String function");
		return null;
	}