val london_crime_records_DS = spark.read.format("org.apache.spark.csv").
      option("header", true).option("inferSchema", true).
      csv("C:\\Users\\Luk3r\\Desktop\\london-crime\\CityofLondonPoliceRecords.csv").
      cache();

london_crime_records_DS.union(metropolitan_crime_records_DS).dropDuplicates("Crime type").withColumn("id", functions.monotonically_increasing_id).select("id","Crime type").collect().foreach(x => println(x))