code: def test_datetime_conversion():
      art = wandb.Artifact("A", "B")
      t = wandb.Table(
          columns=["dt", "t", "np", "d"],
          data=[
              [
                  datetime.datetime(2000, 12, d),
                  datetime.date(2000, 12, d),
                  np.datetime64(
                      "2000-12-" + ("0" if d < 10 else "") + str(d)
                  ),
                  d,
              ]
              for d in range(1, 3)
          ],
      )
      json = t.to_json(art)
      assert json["data"] == [
          [975628800000, 975628800000, 975628800000, 1],
          [975715200000, 975715200000, 975715200000, 2],
      ]
  
file_path: wandb/tests/pytest_tests/unit_tests/test_tables.py
imports: import datetime
  import numpy
  import pytest
  import wandb
label_desc: Use image node_id 8 for calling a global function with example usage: test_datetime_conversion() without return types