class_docstr: A dataset wrapping over a RecordIO (.rec) file.
  
  Each sample is a string representing the raw content of an record.
  
  Parameters
  ----------
  filename : str
      Path to rec file.
code: def __init__(self, filename):
      self.idx_file = os.path.splitext(filename)[0] + ".idx"
      self.filename = filename
      self._record = recordio.MXIndexedRecordIO(
          self.idx_file, self.filename, "r"
      )
  
imports: import os
  from ...None import recordio, ndarray
  from ...util import default_array
label_desc: Use image node_id 1 to create a new RecordFileDataset object from inherited base classes: Dataset with example: obj = RecordFileDataset(filename)