code: def _get_head_pos_sim(raw):
      head_pos_sim = dict()
      # these will be at 1., 2., ... s
      shifts = [[0.001, 0.0, -0.001], [-0.001, 0.001, 0.0]]
  
      for time_key, shift in enumerate(shifts):
          # Create 4x4 matrix transform and normalize
          temp_trans = deepcopy(raw.info["dev_head_t"])
          temp_trans["trans"][:3, 3] += shift
          head_pos_sim[time_key + 1.0] = temp_trans["trans"]
      return head_pos_sim
  
imports: from copy import deepcopy
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from mne import Epochs, SourceEstimate, VolSourceEstimate, convert_forward_solution, create_info, find_events, fit_dipole, make_ad_hoc_cov, make_bem_solution, make_forward_solution, make_sphere_model, pick_types, read_bem_solution, read_cov, read_source_spaces, read_trans, setup_source_space, setup_volume_source_space, transform_surface_to
  from mne._fiff.constants import FIFF
  from mne.bem import _surfaces_to_bem
  from mne.chpi import compute_chpi_amplitudes, compute_chpi_locs, compute_head_pos, get_chpi_info, read_head_pos
  from mne.datasets import testing
  from mne.io import RawArray, read_raw_fif
  from mne.label import Label
  from mne.simulation import add_chpi, add_ecg, add_eog, add_noise, simulate_raw, simulate_sparse_stc
  from mne.simulation.source import SourceSimulator
  from mne.source_space._source_space import _compare_source_spaces
  from mne.surface import _get_ico_surface
  from mne.tests.test_chpi import _assert_quats
  from mne.utils import catch_logging
label_desc: Use image node_id 5 for calling a global function with example usage: _get_head_pos_sim(raw) and returns: head_pos_sim