class_docstr: FoldFile is the realisation of the interface of FoldStorage. It always saves data to file before reset them.
  All files place to the special directory 'folds'.
class_docstr_tok: ["FoldFile","is","the","realisation","of","the","interface","of","FoldStorage",".","It","always","saves","data","to","file","before","reset","them",".","All","files","place","to","the","special","directory","'folds","'","."]
code: def close(self):
      if self._file is None:
          raise CatBoostError(
              "Trying to close None {}".format(self._file_path)
          )
  
      self._file.close()
      self._file = None
  
imports: from __future__ import print_function
  import os
  from ..None import CatBoostError
  from ..eval.log_config import get_eval_logger
  from .utils import make_dirs_if_not_exists
label_desc: Use image node_id 8 for calling the _FoldFile obj's underlying member method code with example usage: obj.close() without return types