Set the default database for this Proxy object.
        :param database_name: A string naming the database

def database(self, database_name):
        """
        Set the default database for this Proxy object.
        :param database_name: A string naming the database
        """
        if database_name and MongoDB.valid_mongodb_name(database_name):
            self._database = self.client[database_name]
        else:
            raise ShellError(f"'{database_name}' is not a valid database name")