def _fix_reindent(self, result):
        """Fix a badly indented line.

        This is done by adding or removing from its initial indent only.

        """
        num_indent_spaces = int(result['info'].split()[1])
        line_index = result['line'] - 1
        target = self.source[line_index]

        self.source[line_index] = ' ' * num_indent_spaces + target.lstrip()