def calculate_pool_chunksize(num_checkers, num_jobs):
    """Determine the chunksize for the multiprocessing Pool.

    - For chunksize, see: https://docs.python.org/3/library/multiprocessing.html#multiprocessing.pool.Pool.imap  # noqa
    - This formula, while not perfect, aims to give each worker two batches of
      work.
    - See: https://gitlab.com/pycqa/flake8/merge_requests/156#note_18878876
    - See: https://gitlab.com/pycqa/flake8/issues/265
    """
    return max(num_checkers // (num_jobs * 2), 1)
