python indexing with booleans?

I saw some code today that surprised me. You can slice arrays using boolean True and False as indexes! See the following examples.

>>> l = list(range(4))
>>> l[:]
[0, 1, 2, 3]
>>> l[True:]
[1, 2, 3]
>>> l[False:]
[0, 1, 2, 3]
>>> l[False]
0
>>> l[True]
1