<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def filter(self, path_filters):
 """ Filters the loaded AttrTree using the supplied path_filters. """

        if not path_filters: return self

        # Convert string path filters
        path_filters = [tuple(pf.split('.')) if not isinstance(pf, tuple)
                        else pf for pf in path_filters]

        # Search for substring matches between paths and path filters
        new_attrtree = self.__class__()
        for path, item in self.data.items():
            if any([all([subpath in path for subpath in pf]) for pf in path_filters]):
                new_attrtree.set_path(path, item)

        return new_attrtree