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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_bucket(seq_len: int, buckets: List[int]) -> Optional[int]: """ Given sequence length and a list of buckets, return corresponding bucket. :param seq_len: Sequence length. :param buckets: List of buckets. :return: Chosen bucket. """

    bucket_idx = bisect.bisect_left(buckets, seq_len)
    if bucket_idx == len(buckets):
        return None
    return buckets[bucket_idx]