new_contents: import sys
  import random
  import predictionio
  
  FILE_NAME = 'dummy_data.json'
  MAX_USER = 20000000
  MAX_REPO = 50000000
  
  def main():
      exporter = new_exporter(FILE_NAME)
      for user_id in range(MAX_USER):
          items = new_items()
          print 'user {} has {} items'.format(user_id, len(items))
          for item_id in items:
               new_event(exporter, user_id, item_id)
      exporter.close()
  
  def new_exporter(file_name):
      return predictionio.FileExporter(file_name=file_name)
  
  def new_items():
      item_count = new_item_count()
      sample = [new_item_id() for _ in range(item_count)]
      return list(set(sample)) # dedupe
  
  def new_item_count():
      return int(random.betavariate(0.3, 0.5) * 100)
  
  def new_item_id():
      sample = int(random.expovariate(1.0) * (MAX_REPO/5))
      return str(min(sample, MAX_REPO))
  
  def new_event(exporter, user_id, item_id):
      exporter.create_event(
          event="star",
          entity_type="user",
          entity_id=user_id,
          target_entity_type="item",
          target_entity_id=item_id)
  
  if __name__ == '__main__':
      main()
  
subject: Add generate_dummy_data.py