code: def isoformat_test(dt_value):
      if isinstance(dt_value, np.datetime64):
          return str(dt_value)
      elif isinstance(dt_value, datetime.datetime):
          return dt_value.isoformat()
      else:
          raise ValueError(
              "Unsupported date type: {}".format(type(dt_value))
          )
  
imports: import pytest
  import plotly.io.json
  import plotly.graph_objects
  import plotly.express
  import numpy
  import pandas
  import json
  import datetime
  import re
  import sys
  import warnings
  from pytz import timezone
  from _plotly_utils.optional_imports import get_module
label_desc: Use image node_id 3 for calling a global function with example usage: isoformat_test(dt_value) and returns: str, dt_value