code: def load(cls, database, doc_id):
          
          doc = database.get(doc_id)
          if doc is None:
              return None
          return cls.wrap(doc)
docs: Load a specific document from the given database.
  
          :param database: the `Database` object to retrieve the document from
          :param doc_id: the document ID
          :return: the `Document` instance, or `None` if no document with the
                   given ID was found