class_docstr: A simple linear model built on statmodels.
code: def fit(self, X, Y, Z, data, **kwargs):
      self.estimator = self._model(X, Y, Z, data, **kwargs).fit()
      self.ate = self.estimator.params[X]
      return self
  
file_path: pgmpy/pgmpy/estimators/LinearModel.py
imports: import statsmodels.api
  from statsmodels.api import OLS, GLS, WLS
label_desc: Use image node_id 3 for calling the LinearEstimator obj's underlying member method code with example usage: obj.fit(X, Y, Z, data) and returns: self