docstr: The trend used in the cointegrating regression
docstr_tok: ["The","trend","used","in","the","cointegrating","regression"]
code: def trend(self) -> str:
      """The trend used in the cointegrating regression"""
      return self._trend
  
imports: from __future__ import annotations
  from typing import Any, NamedTuple, cast
  import pandas
  from statsmodels.iolib.summary import Summary
  from statsmodels.regression.linear_model import OLS, RegressionResults
  import arch.covariance.kernel
  from arch.typing import ArrayLike1D, ArrayLike2D, UnitRootTrend
  from arch.utility.array import ensure1d, ensure2d
  from arch.utility.timeseries import add_trend
label_desc: Use image node_id 2 for calling the ResidualCointegrationTestResult obj's underlying member method code with example usage: obj.trend() and returns: self