def ContentGenerator(csv_file,
                     batch_size,
                     create_csv_reader=csv.reader,
                     create_csv_writer=csv.writer):
  """Retrieves CSV data up to a batch size at a time.

  Args:
    csv_file: A file-like object for reading CSV data.
    batch_size: Maximum number of CSV rows to yield on each iteration.
    create_csv_reader, create_csv_writer: Used for dependency injection.

  Yields:
    Tuple (entity_count, csv_content) where:
      entity_count: Number of entities contained in the csv_content. Will be
        less than or equal to the batch_size and greater than 0.
      csv_content: String containing the CSV content containing the next
        entity_count entities.
  """
  try:
    csv.field_size_limit(800000)
  except __HOLE__:

    pass

  reader = create_csv_reader(csv_file, skipinitialspace=True)
  exhausted = False

  while not exhausted:
    rows_written = 0
    content = StringIO.StringIO()
    writer = create_csv_writer(content)
    try:
      for i in xrange(batch_size):
        row = reader.next()
        writer.writerow(row)
        rows_written += 1
    except StopIteration:
      exhausted = True

    if rows_written > 0:
      yield rows_written, content.getvalue()
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/tools/bulkload_client.py/ContentGenerator