class_docstr: Raw object from FIL-OPMEG formatted data.
  
  Parameters
  ----------
  binfile : path-like
      Path to the MEG data binary (ending in ``'_meg.bin'``).
  precision : str, optional
      How is the data represented? ``'single'`` if 32-bit or
      ``'double'`` if 64-bit (default is single).
  %(preload)s
  
  Returns
  -------
  raw : instance of RawFIL
      The raw data.
      See :class:`mne.io.Raw` for documentation of attributes and methods.
  
  See Also
  --------
  mne.io.Raw : Documentation of attributes and methods of RawFIL.
docstr: Read a chunk of raw data.
docstr_tok: ["Read","a","chunk","of","raw","data","."]
code: def _read_segment_file(self, data, idx, fi, start, stop, cals, mult):
      """Read a chunk of raw data."""
      si = self._raw_extras[fi]
      _read_segments_file(
          self, data, idx, fi, start, stop, cals, mult, dtype=si["dt"]
      )
  
imports: import json
  import pathlib
  import numpy
  from ..._fiff._digitization import _make_dig_points
  from ..._fiff.constants import FIFF
  from ..._fiff.meas_info import _empty_info
  from ..._fiff.utils import _read_segments_file
  from ..._fiff.write import get_new_file_id
  from ...transforms import Transform, apply_trans, get_ras_to_neuromag_trans
  from ...utils import _check_fname, fill_doc, verbose, warn
  from ..base import BaseRaw
  from .sensors import _get_plane_vectors, _get_pos_units, _refine_sensor_orientation, _size2units
label_desc: Use image node_id 2 for calling the RawFIL obj's underlying member method code with example usage: obj._read_segment_file(data, idx, fi, start, stop, cals, mult) without return types