Install libppi-html-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libppi-html-perl
module to highlight Perl code using PPI
PPI::HTML is a Perl module which uses the PPI (a Perl Parsing Interface, see libppi-perl) module to create syntax-highlighted HTML documents from Perl code. It supports extensibility through stylesheets and provides an easy facility to change colours of your output.