'Returns an initialized memcache client.  Used by the constructor.'

def import_preferred_memcache_lib(self, servers):

    try:
        import pylibmc
    except ImportError:
        pass
    else:
        return pylibmc.Client(servers)
    try:
        from google.appengine.api import memcache
    except ImportError:
        pass
    else:
        return memcache.Client()
    try:
        import memcache
    except ImportError:
        pass
    else:
        return memcache.Client(servers)
    try:
        import libmc
    except ImportError:
        pass
    else:
        return libmc.Client(servers)
