code: def via_omkey(self, omkey, det_id):
          
          du, floor = omkey
          try:
              return DOM.from_json([
                  d for d in self._json if d["DU"] == du and d["Floor"] == floor
                  and d["DetOID"] == det_id
              ][0])
          except IndexError:
              log.critical(
                  "No DOM found for OMKey '{0}' and DetOID '{1}'.".format(
                      omkey, det_id
                  )
              )
docs: Return DOM for given OMkey (DU, floor)