'Remove registered serializer with ``name``.
Raises a :class:`ValueError` if there is no such registered
serializer.
:param name: Name of serializer to remove
:type name: ``unicode`` or ``str``
:returns: serializer object'

def unregister(self, name):

    if (name not in self._serializers):
        raise ValueError(u'No    such    serializer    registered    :    {0}'.format(name))
    serializer = self._serializers[name]
    del self._serializers[name]
    return serializer
