Crawl within directory for files conditionally with pathlib

crawl.py

import pathlib
from typing import Callable, List

def crawl_dirs_for_condition(root: pathlib.Path, file_item_condition: Callable) -> List[pathlib.Path]:
        """Crawl root dir for files,
        path file path to file_item_condition function,
        if file_item_condition(file_path) returns true,
        append file path to files.

        Returns
        -------
        files: List[pathlib.Path] 
            All file paths inside root fulfilling file_item_condditions
        """

        files = list()

        def _crawl(root):
            for item in root.iterdir():
                if item.is_file():
                    if file_item_condition(item) and item not in files:
                        files.append(item)
                elif item.is_dir():
                    _crawl(item)

        _crawl(root)

        return files