'Load one epoch from disk.
Returns
data : array | str | None
If string it\'s details on rejection reason.
If None it means no data.'

@verbose
def _get_epoch_from_raw(self, idx, verbose=None):

    if (self._raw is None):
        raise ValueError('An    error    has    occurred,    no    valid    raw    file    found.    Please    report    this    to    the    mne-python    developers.')
    sfreq = self._raw.info['sfreq']
    event_samp = self.events[(idx, 0)]
    first_samp = self._raw.first_samp
    start = int(round((event_samp + (self._raw_times[0] * sfreq))))
    start -= first_samp
    stop = (start + len(self._raw_times))
    data = self._raw._check_bad_segment(start, stop, self.picks, self.reject_by_annotation)
    return data
