获取当前时间减去 xx时，xx分，xx秒

import datetime

# 当前时间减去两分钟
ctime = datetime.datetime.now() + datetime.timedelta(minutes=-2)

# 当前时间减去两小时
ctime = datetime.datetime.now() + datetime.timedelta(hours=-2)

... 

# 点进 timedelta 查看源码可以看到以下参数都可以自己设置

class timedelta(SupportsAbs[timedelta]):
    min: ClassVar[timedelta]
    max: ClassVar[timedelta]
    resolution: ClassVar[timedelta]

    if sys.version_info >= (3, 6):
        def __init__(self, days: float = ..., seconds: float = ..., microseconds: float = ...,
                     milliseconds: float = ..., minutes: float = ..., hours: float = ...,
                     weeks: float = ..., *, fold: int = ...) -> None: ...
    else:
        def __init__(self, days: float = ..., seconds: float = ..., microseconds: float = ...,
                     milliseconds: float = ..., minutes: float = ..., hours: float = ...,
                     weeks: float = ...) -> None: ...
　　...