Insert Method
it is used to returns an integer that speaks to the area of the substring inside the string.
Just try to answer some questions as well, then you can keep a nice balance.
ps. Only answer the questions you know.
I suggest you to read OpenSSL changelogs to make it more clear. As there's not enough space to describe how it works. But heartbleed resistan version was 1.0.2, as I know.