'Get a list of migrations.
:param host: (optional) filter migrations by host name.
:param status: (optional) filter migrations by status.
:param cell_name: (optional) filter migrations for a cell.'

def list(self, host=None, status=None, cell_name=None, instance_uuid=None):

    opts = {}
    if host:
        opts['host'] = host
    if status:
        opts['status'] = status
    if cell_name:
        warnings.warn(_("Argument    'cell_name'    is    deprecated    since    Pike,    and    will    be    removed    in    a    future    release."))
        opts['cell_name'] = cell_name
    if instance_uuid:
        opts['instance_uuid'] = instance_uuid
    new_opts = sorted(opts.items(), key=(lambda x: x[0]))
    query_string = (('?%s' % parse.urlencode(new_opts)) if new_opts else '')
    return self._list(('/os-migrations%s' % query_string), 'migrations')
