class_docstr: Regression tree for XGBoost
  - Reference -
  http://xgboost.readthedocs.io/en/latest/model.html
class_docstr_tok: ["Regression","tree","for","XGBoost","-","Reference","-","http",":","\/\/xgboost.readthedocs.io\/en\/latest\/model.html"]
code: def fit(self, X, y):
      self._impurity_calculation = self._gain_by_taylor
      self._leaf_value_calculation = self._approximate_update
      super(XGBoostRegressionTree, self).fit(X, y)
  
imports: from __future__ import division, print_function
  import numpy
  from mlfromscratch.utils import divide_on_feature, train_test_split, standardize, mean_squared_error
  from mlfromscratch.utils import calculate_entropy, accuracy_score, calculate_variance
label_desc: Use image node_id 5 for calling the XGBoostRegressionTree obj's underlying member method code with example usage: obj.fit(X, y) without return types