Python中單個下劃線「 _」變量的用途是什麼？ - What is the purpose of the single underscore 「_」 variable in Python?

問題：

What is the meaning of _ after for in this code? 這段代碼中_ after for的含義是什麼？

if tbh.bag:
   n = 0
   for _ in tbh.bag.atom_set():
      n += 1

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解決方案：

參考一： https://stackoom.com/question/Oj51/Python中單個下劃線-變量的用途是什麼
參考二： https://oldbug.net/q/Oj51/What-is-the-purpose-of-the-single-underscore-variable-in-Python