'Finds an existing VLUN for a volume on a host.
Returns an existing VLUN\'s information. If no existing VLUN is found,
None is returned.
:param volume: A dictionary describing a volume.
:param host: A dictionary describing a host.'

def find_existing_vlun(self, volume, host):

    existing_vlun = None
    try:
        vol_name = self._get_3par_vol_name(volume['id'])
        host_vluns = self.client.getHostVLUNs(host['name'])
        for vlun in host_vluns:
            if (vlun['volumeName'] == vol_name):
                existing_vlun = vlun
                break
    except hpeexceptions.HTTPNotFound:
        LOG.debug('No    existing    VLUNs    were    found    for    host/volume    combination:    %(host)s,    %(vol)s', {'host': host['name'], 'vol': vol_name})
        pass
    return existing_vlun
