Using double square brackets?

Question

In a file using an older version of Python, I found the following piece of code:

PROP_UI_COMBO = 'Prop_UI_ComboBox'
PROP_UI_COMBO[[]] = [_[1], [x for x in range(-1, 10)] + [26, 28, 30]]

And I'm wondering what it means to set PROP_UI_COMBO[[]] . What do the double brackets mean? Also, (I may be wrong) I believe that _[1] is just the temporary list of [x for x in range(-1, 10)] . So as my question presents, what is the [[]] for, and what is the equivalent in Python 3.4?

Answer 1

这两行不是由Python执行的 - 如果是，则会引发异常。