helps iterate through all the file parsers
        each filter is applied individually to the
        same set of `filepaths`

def _filter_filepaths(self, filepaths):
        """
        helps iterate through all the file parsers
        each filter is applied individually to the
        same set of `filepaths`
        """
        if self.file_filters:
            plugin_filepaths = set()
            for file_filter in self.file_filters:
                plugin_paths = file_filter(filepaths)
                plugin_filepaths.update(plugin_paths)
        else:
            plugin_filepaths = filepaths

        return plugin_filepaths