docs: def _ensure_env(self, env: Union[jinja2.Environment, None]):
          """
          Make sure the jinja environment is minimally configured.
          """
          if not env:
              env = jinja2.Environment()
          if not env.loader:
              env.loader = jinja2.FunctionLoader(lambda filename: self._cache[filename])
          if 'faker' not in env.globals:
              faker = Faker()
              faker.seed(1234)
              env.globals['faker'] = faker
          if 'random_model' not in env.globals:
              env.globals['random_model'] = jinja2.contextfunction(random_model)
          if 'random_models' not in env.globals:
              env.globals['random_models'] = jinja2.contextfunction(random_models)
          return env