Where is the "from __future__ import braces" code?

I was wondering what is exactly the code that executed on the command:

>>> from __future__ import braces
SyntaxError: not a chance

so, since python is open-sourced I opened C:\Python27\Lib\__future__.py and looked. surprisingly, I found nothing there that handle importing braces module.

so, my question is, where is the code that handle this? what happen when I run that command?

The code is in future.c:

future_check_features(PyFutureFeatures *ff, stmt_ty s, const char *filename)
...
  else if (strcmp(feature, "braces") == 0) {
    PyErr_SetString(PyExc_SyntaxError,
        "not a chance");
    PyErr_SyntaxLocation(filename, s->lineno);
    return 0;
  }