code: def op_groupby(df, column_names):
      df_aggregation = df.groupBy(column_names).count()
      return df_aggregation
  
file_path: data-engineering-zoomcamp/06-streaming/python/streams-example/pyspark/streaming.py
imports: from pyspark.sql import SparkSession
  import pyspark.sql.functions
  from settings import RIDE_SCHEMA, CONSUME_TOPIC_RIDES_CSV, TOPIC_WINDOWED_VENDOR_ID_COUNT
label_desc: Use image node_id 7 for calling a global function with example usage: op_groupby(df, column_names) and returns: df_aggregation