code: def test_julian_conversions():
      """Test julian calendar conversions."""
      # https://aa.usno.navy.mil/data/docs/JulianDate.php
      # A.D. 1922 Jun 13  12:00:00.0  2423219.000000
      # A.D. 2018 Oct 3   12:00:00.0  2458395.000000
  
      jds = [2423219, 2458395, 2445701]
      dds = [
          datetime(1922, 6, 13, 12, 0, 0, tzinfo=timezone.utc),
          datetime(2018, 10, 3, 12, 0, 0, tzinfo=timezone.utc),
          datetime(1984, 1, 1, 12, 0, 0, tzinfo=timezone.utc),
      ]
      cals = [(1922, 6, 13), (2018, 10, 3), (1984, 1, 1)]
  
      for dd, cal, jd in zip(dds, cals, jds):
          assert dd == _julian_to_dt(jd)
          assert cal == _julian_to_cal(jd)
  
          assert jd == _dt_to_julian(dd)
          assert jd == _cal_to_julian(cal[0], cal[1], cal[2])
  
imports: from copy import deepcopy
  from datetime import datetime, timezone
  from io import StringIO
  from pathlib import Path
  import numpy
  import pytest
  from numpy.testing import assert_allclose, assert_array_equal
  from scipy import sparse
  from mne import pick_types, read_cov, read_evokeds
  from mne._fiff.pick import _picks_by_type
  from mne.epochs import make_fixed_length_epochs
  from mne.io import read_raw_fif
  from mne.time_frequency import tfr_morlet
  from mne.utils import _PCA, _apply_scaling_array, _apply_scaling_cov, _array_equal_nan, _cal_to_julian, _custom_lru_cache, _dt_to_julian, _freq_mask, _get_inst_data, _julian_to_cal, _julian_to_dt, _reg_pinv, _ReuseCycle, _time_mask, _undo_scaling_array, _undo_scaling_cov, compute_corr, create_slices, grand_average, hashfunc, numerics, object_diff, object_hash, object_size, random_permutation, sum_squared
  from mne.utils.numerics import _LRU_CACHE_MAXSIZES, _LRU_CACHES
label_desc: Use image node_id 16 for calling a global function with example usage: test_julian_conversions() without return types