Import libraries in spark gbt regressor

import pyspark
from pyspark.sql import SparkSession
from pyspark.ml.regression import GBTRegressor
from pyspark.ml.feature import StringIndexer, VectorAssembler
from pyspark.ml.feature import VectorAssembler
from pyspark.ml import Pipeline
from pyspark.ml.evaluation import BinaryClassificationEvaluator
conf = pyspark.SparkConf().setAppName("Gradient Boosted Tree Regressor")
sc = SparkContext.getOrCreate(conf=conf)