How to use the whitenoise.responders.StaticFile function in whitenoise

def test_last_modified_not_set_when_mtime_is_zero():
    class FakeStatEntry(object):
        st_mtime = 0
        st_size = 1024
        st_mode = stat.S_IFREG

    stat_cache = {__file__: FakeStatEntry()}
    responder = StaticFile(__file__, [], stat_cache=stat_cache)
    response = responder.get_response("GET", {})
    response.file.close()
    headers_dict = Headers(response.headers)
    assert "Last-Modified" not in headers_dict
    assert "ETag" not in headers_dict

def get_static_file(self, path, url, stat_cache=None):
        # Optimization: bail early if file does not exist
        if stat_cache is None and not os.path.exists(path):
            raise MissingFileError(path)
        headers = Headers([])
        self.add_mime_headers(headers, path, url)
        self.add_cache_headers(headers, path, url)
        if self.allow_all_origins:
            headers["Access-Control-Allow-Origin"] = "*"
        if self.add_headers_function:
            self.add_headers_function(headers, path, url)
        return StaticFile(
            path,
            headers.items(),
            stat_cache=stat_cache,
            encodings={"gzip": path + ".gz", "br": path + ".br"},
        )