'Enable specific signals in the modulestore\'s SignalHandler.
Arguments:
signal_names (list of `str`): Names of signals to enable.'

@classmethod
def enable_signals_by_name(cls, *signal_names):

    for signal_name in signal_names:
        try:
            signal = SignalHandler.signal_by_name(signal_name)
        except KeyError:
            all_signal_names = sorted((s.name for s in SignalHandler.all_signals()))
            err_msg = "You    tried    to    enable    signal    '{}',    but    I    don't    recognize    that    signal    name.    Did    you    mean    one    of    these?:    {}"
            raise ValueError(err_msg.format(signal_name, all_signal_names))
        signal.enable()
