code: def test_linear(self):
      seriesB: TimeSeries = TimeSeries.from_times_and_values(
          self.time,
          np.array(self.lin[:10] + [np.nan] * 10 + self.lin[-10:]),
      )
  
      # Check for linear interpolation part
      assert self.series2 == fill_missing_values(seriesB, "auto")
  
file_path: darts/darts/tests/utils/test_missing_values.py
imports: import numpy
  import pandas
  from darts import TimeSeries
  from darts.utils.missing_values import fill_missing_values, missing_values_ratio
label_desc: Use image node_id 2 for calling the TestMissingValues obj's underlying member method code with example usage: obj.test_linear() without return types