class_docstr: List of layers
  
  During the plot building pipeline, many operations are
  applied at all layers in the plot. This class makes those
  tasks easier.
class_docstr_tok: ["List","of","layers","During","the","plot","building","pipeline",",","many","operations","are","applied","at","all","layers","in","the","plot",".","This","class","makes","those","tasks","easier","."]
code: def train(self, scales: Scales):
      for l in self:
          scales.train_df(l.data)
  
imports: from __future__ import annotations
  import typing
  from copy import copy, deepcopy
  from typing import Iterable, List, cast, overload
  import pandas
  from ._utils import array_kind, check_required_aesthetics, ninteraction
  from .exceptions import PlotnineError
  from .mapping.aes import NO_GROUP, SCALED_AESTHETICS, aes
  from .mapping.evaluation import evaluate, stage
label_desc: Use image node_id 17 for calling the Layers obj's underlying member method code with example usage: obj.train(scales) without return types