'Discover all entries with svname = \'BACKEND\' and return a list of their corresponding
pxnames'

def discover_all_backends(self):

    data = self.execute('show    stat', 200, False).lstrip('#    ')
    r = csv.DictReader(data.splitlines())
    return tuple(map((lambda d: d['pxname']), filter((lambda d: (d['svname'] == 'BACKEND')), r)))
