Array: Insert with negative index [duplicate]

Question

-1 is not inserting the "hello" at the last index of the array

If I have an array, x:

>>> x = [1, 2, 3] then
>>> x.insert(-1, "hello")
>>> print(x)
[1, 2, 'hello', 3]

Why -1 is not inserting the "hello" at the last index of the array? As -1 index is refered to the last item of the list, so I was expecting:

[1, 2, 3, "hello"]

Answer 1

Running help on method will usually give you the answer for these kind of questions:

help(list.insert)
#Help on method_descriptor:
#
#insert(self, index, object, /)
#    Insert object before index.