class_docstr: Scale channel types using constant values.
code: def fit_transform(self, X, y=None):
      return self.fit(X, y).transform(X)
  
imports: import numpy
  from .._fiff.pick import _pick_data_channels, _picks_by_type, _picks_to_idx, pick_info, pick_types
  from ..cov import _check_scalings_user
  from ..filter import filter_data
  from ..time_frequency import psd_array_multitaper
  from ..utils import _check_option, _validate_type, fill_doc, verbose
  from .base import BaseEstimator
  from .mixin import TransformerMixin
label_desc: Use image node_id 5 for calling the _ConstantScaler obj's underlying member method code with example usage: obj.fit_transform(X, y) and returns: self