import os, sys

def file_fliter(folder:str, file_ext:str, sort_format):

    files_List = os.listdir(folder)
    target_files = []

    # flitered by file extention name
    for file in files_List:
        if file.split('.')[-1] == file_ext:
            target_files.append(file)
    # sort the list by the sort_format
    target_files.sort(key=sort_format)

    return target_files