/**
  * @param ext the file extension
  * @return whether the pack file extensions is known to exist.
  */
 public boolean hasFileExt(PackExt ext) {
   return (extensions & ext.getBit()) != 0;
 }
 /**
  * Adds the pack file extension to the known list.
  *
  * @param ext the file extension
  */
 public void addFileExt(PackExt ext) {
   extensions |= ext.getBit();
 }