code: public static Frame parseFrame(Key okey, File ...files) {
      assert files.length > 0 : "Ups. No files to parse!";
      for (File f : files)
        if (!f.exists())
          throw new RuntimeException("File not found " + f);
      // Create output key if not specified
      if(okey == null)
        okey = Key.make(files[0].getName());
  
      Key[] fkeys = new Key[files.length];
      int cnt = 0;
      for (File f : files) fkeys[cnt++] = NFSFileVec.make(f);
      return parseFrame(okey, fkeys);
    }
docs: Parse given file into the form of frame represented by the given key.
  
  @param okey  destination key for parsed frame
  @param files  files to parse
  @return a new frame