Slices

Question

Code:
squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[-2:6])
print(squares[3:8])
print(squares[0:1])
Result:
[]
[9, 16, 25, 36, 49]
[0]

As you see when I change the slice value from [2:6] to [-2,6] then as a result empty output occurs ( [] ).why the value between -2 to 6 squares are not listed.

Secondly,
code:
squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[-2:9])
print(squares[3:8])
print(squares[0:1])
Result:
[64]
[9, 16, 25, 36, 49]
[0]

In this I change slices to [-2,9] but in this single output is listed. Why such thing occurs.

Answer 1

-2 means the second number from the end.
And if the ending index of the slice is equal to or less than the beginning index, it returns no item.

Answer 2

Here are some examples
https://code.sololearn.com/cXNzv56rgiyL