code: def test_base_iso_format():
      mock_time_str = "2022-04-14 14:42:00"
      mock_time = datetime.strptime(mock_time_str, "%Y-%m-%d %H:%M:%S")
      assert default(mock_time) == "2022-04-14T14:42:00"
  
file_path: pyecharts/test/test_base.py
imports: from datetime import datetime
  from unittest.mock import patch
  from nose.tools import assert_equal, assert_in, assert_not_in
  from pyecharts.charts import Bar
  from pyecharts.commons import utils
  from pyecharts.datasets import EXTRA
  from pyecharts.options import InitOpts, RenderOpts
  from pyecharts.globals import CurrentConfig
  from pyecharts.charts.base import Base, default
  from pyecharts.options.global_options import AnimationOpts
label_desc: Use image node_id 7 for calling a global function with example usage: test_base_iso_format() without return types