def write_or_delete_file(self, what, filename, data, force=False):
        """Write `data` to `filename` or delete if empty

        If `data` is non-empty, this routine is the same as ``write_file()``.
        If `data` is empty but not ``None``, this is the same as calling
        ``delete_file(filename)`.  If `data` is ``None``, then this is a no-op
        unless `filename` exists, in which case a warning is issued about the
        orphaned file (if `force` is false), or deleted (if `force` is true).
        """
        if data:
            self.write_file(what, filename, data)
        elif os.path.exists(filename):
            if data is None and not force:
                log.warn(
                    "%s not set in setup(), but %s exists", what, filename
                )
                return
            else:
                self.delete_file(filename)
Write `data` to `filename` or delete if empty

        If `data` is non-empty, this routine is the same as ``write_file()``.
        If `data` is empty but not ``None``, this is the same as calling
        ``delete_file(filename)`.  If `data` is ``None``, then this is a no-op
        unless `filename` exists, in which case a warning is issued about the
        orphaned file (if `force` is false), or deleted (if `force` is true).