docs: public boolean isFixedDisk(String letter) {
  		if (letter.length() != 1) throw new IllegalArgumentException("Supply 1 letter, not: " + letter);
  		char drive = Character.toUpperCase(letter.charAt(0));
  		if (drive < 'A' || drive > 'Z') throw new IllegalArgumentException(
  				"A drive is indicated by a letter, so A-Z inclusive. Not " + drive);
  		return getDriveType(drive + ":\\") == 3L;
  	}