@classmethod<EOL><INDENT>def make_uuid(cls, app_id=None):<DEDENT>
try:<EOL><INDENT>if app_id and isinstance(uuid.UUID(str(app_id), version=<NUM_LIT:4>), uuid.UUID):<EOL><INDENT>return str(app_id)<EOL><DEDENT><DEDENT>except (ValueError, AssertionError):<EOL><INDENT>pass<EOL><DEDENT>return str(uuid.UUID(int=random.getrandbits(<NUM_LIT>)))<EOL>
Generates a new UUID.
        This is a class method and can be called as `Experiment.make_uuid()`.
        Takes an optional `app_id` which is converted to a string and, if it
        is a valid UUID, returned.