def get_mf_ctc_fname(subject, session):
if config.mf_ctc_fname is None:
mf_ctc_fpath = BIDSPath(subject=subject,
session=session,
suffix='meg',
datatype='meg',
root=config.bids_root).meg_crosstalk_fpath
if mf_ctc_fpath is None:
raise ValueError('Could not find Maxwell Filter cross-talk '
'file.')
else:
mf_ctc_fpath = Path(config.mf_ctc_fname)
if not mf_ctc_fpath.exists():
raise ValueError(f'Could not find Maxwell Filter cross-talk '
f'file at {str(mf_ctc_fpath)}.')
return mf_ctc_fpath
