Python 如何根据步长提取短序列？

下面的代码提取窗口大小为100的每个序列中的短序列。窗口将按步长1移动并提取序列。我想提取每个步长为50的短序列。有人能帮我吗

 from Bio import SeqIO

 with open("B.fasta","w") as f:
         for seq_record in SeqIO.parse("A.fasta", "fasta"):
             for i in range(len(seq_record.seq) - 99) :
                f.write(str(">"+seq_record.id) + "\n")
                f.write(str(seq_record.seq[i:i+100]) + "\n")

fasta文件示例：

>hg17_ct_ER_ER_142
CTAAAAAAGTAAAAAAGAAAAAAAGAGAAAGAAAGAATATAGAAGCAACAAGTGTAGATTTACATTCTATTAGACAGTGACCCATTAGACCCGGACAAGGGG

示例输出：

>hg17_ct_ER_ER_142
CTAAAAAAGTAAAAAAGAAAAAAAGAGAAAGAAAGAATATAGAAGCAACAAGTGTAGATTTACATTCTATTAGACAGTGACCCATTAGACCCGGACAAGG
>hg17_ct_ER_ER_142
TAAAAAAGTAAAAAAGAAAAAAAGAGAAAGAAAGAATATAGAAGCAACAAGTGTAGATTTACATTCTATTAGACAGTGACCCATTAGACCCGGACAAGGG
>hg17_ct_ER_ER_142
AAAAAAGTAAAAAAGAAAAAAAGAGAAAGAAAGAATATAGAAGCAACAAGTGTAGATTTACATTCTATTAGACAGTGACCCATTAGACCCGGACAAGGGG

预期输出：

>hg17_ct_ER_ER_142
CTAAAAAAGTAAAAAAGAAAAAAAGAGAAAGAAAGAATATAGAAGCAACA
>hg17_ct_ER_ER_142
AGTGTAGATTTACATTCTATTAGACAGTGACCCATTAGACCCGGACAAGG

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只需将步长选项用于范围函数：

for i in range(0, len(seq_record.seq) - 99, 50) :

可能重复的