# PreTeXt Sample Book: Abstract Algebra (SAMPLE ONLY)

## Section5.2Code Lens

CodeLens is an interactive tool for following program execution, much like a debugger, without the ability to influence flow control or variable values. For use without a server, traces must be computed beforehand. First, we have some trivial programs, to provide minimal testing.
Now some moderately more complicated programs to find teh prime numbers less than $$20\text{.}$$ We do not vouch for the quality of these, or even their correctness!