<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _keep( word_freq: int, min_freq: int, min_len: int, max_len: int, dict_filter: Callable[[str], bool], ):
 """ Keep only Thai words with at least min_freq frequency and has length between min_len and max_len characters """

    if not word_freq or word_freq[1] < min_freq:
        return False

    word = word_freq[0]
    if not word or len(word) < min_len or len(word) > max_len or word[0] == ".":
        return False

    return dict_filter(word)