code: def _read_coil_defs(verbose=None):
      """Read a coil definition file.
  
      Parameters
      ----------
      %(verbose)s
  
      Returns
      -------
      res : list of dict
          The coils. It is a dictionary with valid keys:
          'cosmag' | 'coil_class' | 'coord_frame' | 'rmag' | 'type' |
          'chname' | 'accuracy'.
          cosmag contains the direction of the coils and rmag contains the
          position vector.
  
      Notes
      -----
      The global variable "_extra_coil_def_fname" can be used to prepend
      additional definitions. These are never added to the registry.
      """
      coil_dir = op.join(op.split(__file__)[0], "..", "data")
      coils = list()
      if _extra_coil_def_fname is not None:
          coils += _read_coil_def_file(
              _extra_coil_def_fname, use_registry=False
          )
      coils += _read_coil_def_file(op.join(coil_dir, "coil_def.dat"))
      return coils
  
imports: import os
  import os.path
  from contextlib import contextmanager
  from copy import deepcopy
  from pathlib import Path
  import numpy
  from .._fiff.compensator import get_current_comp, make_compensator
  from .._fiff.constants import FIFF, FWD
  from .._fiff.meas_info import Info, read_info
  from .._fiff.pick import _has_kit_refs, pick_info, pick_types
  from .._fiff.tag import _loc_to_coil_trans, _loc_to_eeg_loc
  from ..bem import ConductorModel, _bem_find_surface, read_bem_solution
  from ..source_estimate import VolSourceEstimate
  from ..source_space._source_space import _complete_vol_src, _ensure_src, _filter_source_spaces, _make_discrete_source_space
  from ..surface import _CheckInside, _normalize_vectors
  from ..transforms import Transform, _coord_frame_name, _ensure_trans, _get_trans, _print_coord_trans, apply_trans, invert_transform, transform_surface_to
  from ..utils import _check_fname, _pl, _validate_type, logger, verbose, warn
  from ._compute_forward import _compute_forwards
  from .forward import _FWD_ORDER, Forward, _merge_fwds, convert_forward_solution
label_desc: Use image node_id 1 for calling a global function with example usage: _read_coil_defs(verbose) and returns: coils