code: def lreg(self, xcol, ycol, name="Regression"):
          
          try:
              x = self.df[xcol].values.reshape(-1, 1)
              y = self.df[ycol]
              lm = linear_model.LinearRegression()
              lm.fit(x, y)
              predictions = lm.predict(x)
              self.df[name] = predictions
          except Exception as e:
              self.err(e, "Can not calculate linear regression")
docs: Add a column to the main dataframe populted with
          the model's linear regression for a column