code: def start_time(request):
      """Get start time of the dataset."""
      return request.param
  
imports: import datetime
  import os
  import numpy
  import pytest
  import xarray
  from pyresample.geometry import AreaDefinition
  from satpy.tests.utils import make_dataid
label_desc: Use image node_id 1 for calling a global function with example usage: start_time(request) and returns: request