'Implemented so that access to ``sequence`` raises a warning.
>>> d = OrderedDict()
>>> d.sequence'

def __getattr__(self, name):

    if (name == 'sequence'):
        warnings.warn('Use    of    the    sequence    attribute    is    deprecated.    Use    the    keys    method    instead.', DeprecationWarning)
        return self._sequence
    else:
        raise AttributeError(("OrderedDict    has    no    '%s'    attribute" % name))
