code: def get_by_id(self, process_name, db_id):
          
          collection_name = self._get_job_collection_name(process_name)
          collection = self.ds.connection(collection_name)
          document = collection.find_one({'_id': ObjectId(db_id)})
  
          if document is None:
              raise LookupError('MongoDB has no job record in collection {0} for {1}'
                                .format(collection, db_id))
          return Job.from_json(document)
docs: method finds a single job record and returns it to the caller