code: def _lin_field_coeff(surf, mult, rmags, cosmags, ws, bins, n_jobs):
      """Parallel wrapper for _do_lin_field_coeff to compute linear coefficients.
  
      Parameters
      ----------
      surf : dict
          Dict containing information for one surface of the BEM
      mult : float
          Multiplier for particular BEM surface (Iso Skull Approach discussed in
          Mosher et al., 1999 and Hämäläinen and Sarvas, 1989 Section III?)
      rmag : ndarray, shape (n_integration_pts, 3)
          3D positions of MEG coil integration points (from coil['rmag'])
      cosmag : ndarray, shape (n_integration_pts, 3)
          Direction of the MEG coil integration points (from coil['cosmag'])
      ws : ndarray, shape (n_integration_pts,)
          Weights for MEG coil integration points
      bins : ndarray, shape (n_integration_points,)
          The sensor assignments for each rmag/cosmag/w.
      %(n_jobs)s
  
      Returns
      -------
      coeff : list
          Linear coefficients with lead fields for each BEM vertex on each sensor
          (?)
      """
      parallel, p_fun, n_jobs = parallel_func(
          _do_lin_field_coeff, n_jobs, max_jobs=len(surf["tris"])
      )
      nas = np.array_split
      coeffs = parallel(
          p_fun(surf["rr"], t, tn, ta, rmags, cosmags, ws, bins)
          for t, tn, ta in zip(
              nas(surf["tris"], n_jobs),
              nas(surf["tri_nn"], n_jobs),
              nas(surf["tri_area"], n_jobs),
          )
      )
      return mult * np.sum(coeffs, axis=0)
  
imports: from copy import deepcopy
  import numpy
  from .._fiff.constants import FIFF
  from ..bem import _import_openmeeg, _make_openmeeg_geometry
  from ..fixes import bincount, jit
  from ..parallel import parallel_func
  from ..surface import _jit_cross, _project_onto_surface
  from ..transforms import apply_trans, invert_transform
  from ..utils import _check_option, _pl, fill_doc, logger, verbose, warn
label_desc: Use image node_id 3 for calling a global function with example usage: _lin_field_coeff(surf, mult, rmags, cosmags, ws, bins, n_jobs) and returns: unknown