s = 'Hello World!'

(python)

what are the ones with the black dots? Thank you.

Expression Calculated Missing s[D] 'W' 6 [2] 'C' s[4: ] 'o Wo' 8 s[: ] 'He' 2 s[O :] 'rld!' 8 [2:100] 'a' [3:1] s S[1:2+ ] 'ello' 3 O [-2] 'b' S[-O] 'H' s[ [ [ :-3] 'or' [-2:] 'bc