docs: def verify_checksum(file_id, pessimistic=False, chunk_size=None, throws=True,
                      checksum_kwargs=None):
      """Verify checksum of a file instance.
  
      :param file_id: The file ID.
      """
      f = FileInstance.query.get(uuid.UUID(file_id))
  
      # Anything might happen during the task, so being pessimistic and marking
      # the file as unchecked is a reasonable precaution
      if pessimistic:
          f.clear_last_check()
          db.session.commit()
      f.verify_checksum(
          progress_callback=progress_updater, chunk_size=chunk_size,
          throws=throws, checksum_kwargs=checksum_kwargs)
      db.session.commit()