As per my simple observations,
s = "Python is great."
- print s[2] = t ,print s[2][1] will be absured because "print s[2]" have only 1 char in output. so print s[2][0] will only work.
- print s[::-1]=.taerg si nohtyP ,print s[::-1][::-1] will do again do that operation on output so we will get original string inverted back.
- so, second bracket applies specified operation in it, on output of first bracket.
