code: def _fit_regression(self, y):
          
  
          if self.regressor is None:
              self.coefs_ = safe_sparse_dot(pinv2(self.hidden_activations_), y)
          else:
              self.regressor.fit(self.hidden_activations_, y)
  
          self.fitted_ = True
docs: fit regression using pseudo-inverse
          or supplied regressor