def set_env(self, *env_varss: Env_VarsType) -> Iterator[None]:
        """Set environment variables.

        All the arguments are dicts of name:value, or None.  All are applied
        to the environment variables.
        """
        old_env_vars = self.env_vars
        self.env_vars = dict(old_env_vars)
        for env_vars in env_varss:
            self.env_vars.update(env_vars or {})
        try:
            yield
        finally:
            self.env_vars = old_env_vars
Set environment variables.

        All the arguments are dicts of name:value, or None.  All are applied
        to the environment variables.
        
benchmark/benchmark.py