【Python入門】文字列の操作をマスターしていこう

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5 Ways to Find the Index of a Substring in Python | Built In

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Count of substrings that start and end with 1 in given Binary String - GeeksforGeeks

JavaScript Substring Examples - Slice, Substr, and Substring Methods in JS

Python Read And Write File: With Examples • Python Land Tutorial

String Slicing in Python - GeeksforGeeks