code: def folder_source(path, folder):
      
      fnames, lbls, all_lbls = read_dirs(path, folder)
      lbl2idx = {lbl:idx for idx,lbl in enumerate(all_lbls)}
      idxs = [lbl2idx[lbl] for lbl in lbls]
      lbl_arr = np.array(idxs, dtype=int)
      return fnames, lbl_arr, all_lbls
docs: Returns the filenames and labels for a folder within a path
      
      Returns:
      -------
      fnames: a list of the filenames within `folder`
      all_lbls: a list of all of the labels in `folder`, where the # of labels is determined by the # of directories within `folder`
      lbl_arr: a numpy array of the label indices in `all_lbls`