code: def test_multi_ts(self):
      series1 = constant_timeseries(value=0.0, length=3)
      series2 = constant_timeseries(value=1.0, length=3)
  
      data = [series1, series2]
  
      mapper1 = InvertibleMapper(
          fn=lambda x: x + 10, inverse_fn=lambda x: x - 10
      )
      mapper2 = InvertibleMapper(
          fn=lambda x: x * 10, inverse_fn=lambda x: x / 10
      )
  
      transformers = [mapper1, mapper2]
      p = Pipeline(transformers)
  
      # when
      transformed = p.transform(data)
      back = p.inverse_transform(transformed)
  
      # then
      assert data == back
  
imports: from typing import Any, Mapping
  import pytest
  from darts import TimeSeries
  from darts.dataprocessing import Pipeline
  from darts.dataprocessing.transformers import BaseDataTransformer, FittableDataTransformer, InvertibleDataTransformer, InvertibleMapper, Mapper
  from darts.utils.timeseries_generation import constant_timeseries
label_desc: Use image node_id 11 for calling the TestPipeline obj's underlying member method code with example usage: obj.test_multi_ts() without return types