查看某个方法的doc

python -m pydoc 方法名

python -m pydoc raw_input

查询结果如下，按ctrl+z退出

raw_input(...)
    raw_input([prompt]) -> string
    
    Read a string from standard input.  The trailing newline is stripped.
    If the user hits EOF (Unix: Ctl-D, Windows: Ctl-Z+Return), raise EOFError.
    On Unix, GNU readline is used if enabled.  The prompt string, if given,
    is printed without a trailing newline before reading.
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