Return a fully-qualified environment_session string.

def environment_session_path(cls, project, environment, user, session):
        """Return a fully-qualified environment_session string."""
        return google.api_core.path_template.expand(
            'projects/{project}/agent/environments/{environment}/users/{user}/sessions/{session}',
            project=project,
            environment=environment,
            user=user,
            session=session,
        )