def _get_wanted_channels(wanted_sig_names, record_sig_names, pad=False):
    """
    Given some wanted signal names, and the signal names contained in a
    record, return the indices of the record channels that intersect.

    Parameters
    ----------
    wanted_sig_names : list
        List of desired signal name strings
    record_sig_names : list
        List of signal names for a single record
    pad : bool, optional
        Whether the output channels is to always have the same number
        of elements and the wanted channels. If True, pads missing
        signals with None.

    Returns
    -------
    wanted_channel_inds

    """
    if pad:
        return [record_sig_names.index(s) if s in record_sig_names else None for s in wanted_sig_names]
    else:
        return [record_sig_names.index(s) for s in wanted_sig_names if s in record_sig_names]