keras pad_序列做什么？

Question

我试图在keras中编写一个文本char-rnn，为此，我必须首先将文本转换为序列，然后填充序列。但我在执行这一步骤时遇到了很多麻烦。我相信这是因为我对这个函数本身（pad_sequence）的理解有偏差或缺乏。我试着用谷歌搜索它，但没有找到任何好的教程，而且在kerasdocs中也没有太多的解释。

有谁能告诉我pad_sequence是怎么回事和什么？为什么我们应该在输入之前填充序列（这里是字符级别）。

请以这篇课文为例？

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