Searchs and returns set of unique names of objects
    which implements MPRIS2 interfaces.

    :returns: set of unique names.
    :type: set

def available_players():
    """Searchs and returns set of unique names of objects
    which implements MPRIS2 interfaces.

    :returns: set of unique names.
    :type: set
    """
    bus = dbus.SessionBus()
    players = set()
    for name in filter(lambda item: item.startswith(MPRIS_NAME_PREFIX),
                       bus.list_names()):
        owner_name = bus.get_name_owner(name)
        players.add(convert(owner_name))
    return players