code: def _loc_to_coil_trans(loc):
      """Convert loc vector to coil_trans."""
      assert loc.shape[-1] == 12
      coil_trans = np.zeros(loc.shape[:-1] + (4, 4))
      coil_trans[..., :3, 3] = loc[..., :3]
      coil_trans[..., :3, :3] = np.reshape(
          loc[..., 3:], loc.shape[:-1] + (3, 3)
      ).swapaxes(-1, -2)
      coil_trans[..., -1, -1] = 1.0
      return coil_trans
  
imports: import html
  import re
  import struct
  from dataclasses import dataclass
  from functools import partial
  from typing import Any
  import numpy
  from scipy.sparse import csc_matrix, csr_matrix
  from ..utils import _check_option, warn
  from ..utils.numerics import _julian_to_cal
  from .constants import FIFF, _ch_coil_type_named, _ch_kind_named, _ch_unit_mul_named, _ch_unit_named, _dig_cardinal_named, _dig_kind_named
label_desc: Use image node_id 2 for calling a global function with example usage: _loc_to_coil_trans(loc) and returns: coil_trans