def format_exc(etype, evalue, etb, context=5, tb_offset=0):
    # some locals
    try:
        etype = etype.__name__
    except AttributeError:
        pass

    # Header with the exception type, python version, and date
    pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
    date = time.ctime(time.time())
    pid = 'PID: %i' % os.getpid()

    head = '%s%s%s\n%s%s%s' % (
        etype, ' ' * (75 - len(str(etype)) - len(date)),
        date, pid, ' ' * (75 - len(str(pid)) - len(pyver)),
        pyver)

    # Drop topmost frames if requested
    try:
        records = _fixed_getframes(etb, context, tb_offset)
    except:
        raise
        print('\nUnfortunately, your original traceback can not be '
              'constructed.\n')
        return ''

    # Get (safely) a string form of the exception info
    try:
        etype_str, evalue_str = map(str, (etype, evalue))
    except:
        # User exception is improperly defined.
        etype, evalue = str, sys.exc_info()[:2]
        etype_str, evalue_str = map(str, (etype, evalue))
    # ... and format it
    exception = ['%s: %s' % (etype_str, evalue_str)]
    frames = format_records(records)
    return '%s\n%s\n%s' % (head, '\n'.join(frames), ''.join(exception[0]))


###############################################################################
Test channel-picking functionality
dataset/ETHPy150Open scikit-learn/scikit-learn/sklearn/externals/joblib/format_stack.py/format_exc--crossover with--dataset/ETHPy150Open mne-tools/mne-python/mne/tests/test_evoked.py/test_pick_channels_mixin