Install libperlx-assert-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libperlx-assert-perl
yet another assertion keyword
PerlX::Assert is a framework for embedding assertions in Perl code. Under normal circumstances, assertions are not checked; they are optimized away at compile time. . However if, at compile time, any of the following environment variables is true, assertions are checked, and if they fail, throw an exception. . - PERL_STRICT - AUTHOR_TESTING - EXTENDED_TESTING - RELEASE_TESTING . That is, assertions will only typically be checked when the test suite is being run on the authors' machine, or otherwise opted into.