docs: def set_mn_controlled_values(request, sysmeta_pyxb, is_modification):
      """See the description of TRUST_CLIENT_* in settings.py."""
      now_datetime = d1_common.date_time.utc_now()
  
      default_value_list = [
          ('originMemberNode', django.conf.settings.NODE_IDENTIFIER, True),
          ('authoritativeMemberNode', django.conf.settings.NODE_IDENTIFIER, True),
          ('serialVersion', 1, False),
          ('dateUploaded', now_datetime, False),
      ]
  
      if not is_modification:
          # submitter cannot be updated as the CN does not allow it.
          default_value_list.append(('submitter', request.primary_subject_str, True))
          # dateSysMetadataModified cannot be updated as it is used for optimistic
          # locking. If changed, it is assumed that optimistic locking failed, and the
          # update is rejected in order to prevent a concurrent update from being lost.
          default_value_list.append(('dateSysMetadataModified', now_datetime, False))
      else:
          sysmeta_pyxb.submitter = None
          sysmeta_pyxb.dateSysMetadataModified = now_datetime
  
      for attr_str, default_value, is_simple_content in default_value_list:
          is_trusted_from_client = getattr(
              django.conf.settings, 'TRUST_CLIENT_{}'.format(attr_str.upper()), False
          )
          override_value = None
          if is_trusted_from_client:
              override_value = (
                  d1_common.xml.get_opt_val(sysmeta_pyxb, attr_str)
                  if is_simple_content
                  else getattr(sysmeta_pyxb, attr_str, None)
              )
          setattr(sysmeta_pyxb, attr_str, override_value or default_value)