summary() fails if called a second time

[xadupre]

Describe the bug

summary() fails if called a second time.

To Reproduce

nlr = OrdinaryLeastSquaresRegressor()
nlr.fit(diabetes_X_train, diabetes_y_train)
nlr.summary()  # ok
nlr.summary()  # fails

produces the following error:

nimbusml\base_predictor.py in summary(self)
    140         Returns model summary.
    141         """
--> 142         if hasattr(self, 'model_summary_') and self.model_summary_:
    143             return self.model_summary_
    144 

pandas\core\generic.py in __nonzero__(self)
   1574         raise ValueError("The truth value of a {0} is ambiguous. "
   1575                          "Use a.empty, a.bool(), a.item(), a.any() or a.all()."
-> 1576                          .format(self.__class__.__name__))
   1577 
   1578     __bool__ = __nonzero__

Desktop

• OS: [Windows]
• Browser [Chrome]
• Version [python 3.7]