Undocumented method for "slice" class

Documentation

The "slice" class has a method "indices" that, when given a length of a sequence, will return a tuple with (start, stop, step) that is adjusted for the length of that sequence. This method is completely undocumented

For example,

x=slice(0, 10, -2)
x.indices(5) #This returns (0, 4, -2)
x.indices(10) #This returns (0, 9, -2)
x.indices(100) #This returns (0, 9, -2)

The only example that I could find in any official Python documents is this, there is a single reference to this method at the bottom of the page. However, as of the lastest version of Python, which is 3.11.0 at the time of writing, using this method in a standard installation of CPython still works.

• PR: gh-99129

從 issue 中連結的 Python slice 類別文件頁面開始，檢查其中如何記錄其方法。為 slice.indices() 新增文件，包括其 length 引數、回傳的 tuple 以及行為範例；當該方法與類別一同獲得描述且範例正確時，即視為完成。