It then builds a new regular expression in indent_pat that matches exactly the same sequence of whitespace at the start of any non-empty line (hence the trailing '\ s').

随后在indent _ pat中构建一个新的正则表达式，精确匹配任何非空行的起始处的相同序列的空白(即拖尾' \ S ')。

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Regular expressions: search word (s) will be regarded as a regular expression (in keyword search words will be treated as a sequence of regular expressions).

正则表达式：搜索单词将作为一个正则表达式(在关键字搜索中，单词被视为正则表达式系列)。

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The most common scenario for matching regular expressions is to start at some point in a character sequence and move forward until all matches have been found and the end of the sequence is reached.

正则表达式匹配最常见的场景是从字符序列的某个点上开始，向前移动，直到找到所有匹配，并到达序列末尾为止。

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