code: def _get_file_units(dataset_id, ds_info):
      """Get file units from metadata."""
      file_units = ds_info.get("file_units")
      if file_units is None:
          LOG.debug("Unknown units for file key '%s'", dataset_id)
      return file_units
  
imports: import logging
  from datetime import datetime, timedelta
  import dask.array
  import numpy
  import xarray
  from satpy.readers.hdf5_utils import HDF5FileHandler
label_desc: Use image node_id 2 for calling a global function with example usage: _get_file_units(dataset_id, ds_info) and returns: file_units