def METHOD_NAME(environ, ctx):
    """Set the `RequestContext` in a WSGI environment.
    After `set_in_environ(e, ctx)`, `from_environ(e) is ctx`. The input
    environment is mutated.
    Args:
      environ: A WSGI environment to update.
      ctx: A new `RequestContext` value.
    """
    environ[_WSGI_KEY] = ctx