code: def test_len_index_dipoles():
      """Test len and indexing of Dipole objects."""
      dipole = read_dipole(fname_dip)
      d0 = dipole[0]
      d1 = dipole[:1]
      _check_dipole(d0, 1)
      _check_dipole(d1, 1)
      _compare_dipoles(d0, d1)
      mask = dipole.gof > 15
      idx = np.where(mask)[0]
      d_mask = dipole[mask]
      _check_dipole(d_mask, 4)
      _compare_dipoles(d_mask, dipole[idx])
  
imports: import os
  import matplotlib.pyplot
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal, assert_array_less
  from mne import Dipole, DipoleFixed, Epochs, Evoked, EvokedArray, SourceEstimate, convert_forward_solution, fit_dipole, head_to_mni, make_ad_hoc_cov, make_fixed_length_events, make_forward_solution, make_sphere_model, pick_info, pick_types, read_cov, read_dipole, read_evokeds, read_forward_solution, read_source_spaces, transform_surface_to, write_evokeds
  from mne._fiff.constants import FIFF
  from mne.bem import _bem_find_surface, read_bem_solution
  from mne.datasets import testing
  from mne.dipole import _BDIP_ERROR_KEYS, get_phantom_dipoles
  from mne.io import read_raw_ctf, read_raw_fif
  from mne.proj import make_eeg_average_ref_proj
  from mne.simulation import simulate_evoked
  from mne.surface import _compute_nearest
  from mne.transforms import _get_trans, apply_trans
  from mne.utils import _record_warnings, requires_mne, run_subprocess
label_desc: Use image node_id 7 for calling a global function with example usage: test_len_index_dipoles() without return types