code: def _get_groups(groups, list_datarrays):
      """Return a dictionary with the list of xr.DataArray associated to each group.
  
      If no groups (groups=None), return all DataArray attached to a single None key.
      Else, collect the DataArrays associated to each group.
      """
      if groups is None:
          return {None: list_datarrays}
  
      return {
          group_name: _get_group_dataarrays(
              group_members, list_datarrays
          )
          for group_name, group_members in groups.items()
      }
  
file_path: satpy/satpy/cf/datasets.py
imports: import logging
  import warnings
  import xarray
  from satpy.writers.cf_writer import CF_DTYPES, CF_VERSION
label_desc: Use image node_id 3 for calling a global function with example usage: _get_groups(groups, list_datarrays) and returns: unknown, dict