def __exec(_code_, _globs_=None, _locs_=None):
      """Execute code in a namespace."""
      if _globs_ is None:
         frame = sys._getframe(1)
         _globs_ = frame.f_globals
         if _locs_ is None:
            _locs_ = frame.f_locals
         del frame
      elif _locs_ is None:
         _locs_ = _globs_
      exec("""exec _code_ in _globs_, _locs_""")