'Modify volume parameters.
A list of valid parameters can be found at https://goo.gl/N0rPEQ
:param      Volume: Volume instance
:type       Volume: :class:`Volume`
:param      parameters: Dictionary with updated volume parameters
:type       parameters: ``dict``
:return: Volume modification status object
:rtype: :class:`VolumeModification'

def ex_modify_volume(self, volume, parameters):

    parameters = (parameters or {})
    volume_type = parameters.get('VolumeType')
    if (volume_type and (volume_type not in VALID_VOLUME_TYPES)):
        raise ValueError(('Invalid    volume    type    specified:    %s' % volume_type))
    parameters.update({'Action': 'ModifyVolume', 'VolumeId': volume.id})
    response = self.connection.request(self.path, params=parameters.copy()).object
    return self._to_volume_modification(response.findall(fixxpath(xpath='volumeModification', namespace=NAMESPACE))[0])
