'Baseline correct evoked data.
Parameters
baseline : tuple of length 2
The time interval to apply baseline correction. If None do not
apply it. If baseline is (a, b) the interval is between "a (s)" and
"b (s)". If a is None the beginning of the data is used and if b is
None then b is set to the end of the interval. If baseline is equal
to (None, None) all the time interval is used. Correction is
applied by computing mean of the baseline period and subtracting it
from the data. The baseline (a, b) includes both endpoints, i.e.
all timepoints t such that a <= t <= b.
verbose : bool, str, int, or None
If not None, override default verbose level (see
:func:`mne.verbose` and :ref:`Logging documentation <tut_logging>`
for more).
Returns
evoked : instance of Evoked
The baseline-corrected Evoked object.
Notes
Baseline correction can be done multiple times.
.. versionadded:: 0.13.0'

@verbose
def apply_baseline(self, baseline=(None, 0), verbose=None):

    self.data = rescale(self.data, self.times, baseline, copy=False)
    return self
