why L[3:1]=['?'] become L.insert(3,'?')

[sd44]

在 2010-10-04一的 08:00 -0700，Richard Thomas写道：

> > >>> L=[1,2,3,4]
> > >>> L[3:1]
> > []
> > >>> print L
> > [1, 2, 3, 4]
> > >>> L[3:1]=['?']

> Chard.

thx for all,I know it ^____^
thx