Install libnamespace-autoclean-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libnamespace-autoclean-perl
module to remove imported symbols after compilation
namespace::autoclean is a Perl pragma that keeps your namespace clean by removing all imported symbols at the end of the current package's compile cycle. Perhaps most importantly, this means that imported functions will no longer be made accidentally accessible to users outside of your package via method invocations. . This module differs from namespace::clean (see libnamespace-clean-perl) in that it cleans all imported functions, whether or not the imports happened prior to using the pragma. Things that "look" like a method (according to Class::MOP) will be left alone.