Forgetting
Forgetting
[Cueball sits at computer, coding.]
Cueball: <sniff>
[Cueball lowers his head into his hands and cries.]
[Cueball types again.]

Cueball is writing a piece of code (probably in the programming language C++ ) that removes an item from a data structure called a Linked list (the first two lines of the text). Then, he writes a comment (delimited by the double slashes) relating the code to his personal life. Finally, he adds an assertion , which is normally a formal specification of a condition that should always be true (with which the programmer ensures that, e.g. mass is not negative). But in this case, instead of asserting a software-related predicate, he asserts that "it's going to be okay" - and because of how string literals are treated by the interpreter, the assertion will be true.
An "assert" is a programming statement that allows you to insert sanity checks into your code. For example, if you were writing a program to calculate the speed of a neutrino, then at the end of the calculation you could say:
assert ( velocity_of_neutrino <= speed_of_light );
If the assertion fails, then the program will stop with an error. This would be much better than publishing an embarrassing paper, for example.
Cueball realizes that he cannot forget his emotional event through the use of two commands as he can with a computer, which only makes him feel sad about an unsaid event, the item -- in a sense -- that cannot be removed.  He writes two comments further clarifying his sense of hopelessness over this event, followed by an assertion that "it will be okay," something that has nothing to do with the code he is writing.
The title text explains that assertion in question fails: nobody can be sure that things are going to be okay.
[Cueball sits at computer, coding.]
Cueball: <sniff>
[Cueball lowers his head into his hands and cries.]
[Cueball types again.]
