How do I add a directory to my include path (@INC) at runtime?
  Here are the suggested ways of modifying your include path:

      the PERLLIB environment variable
      the PERL5LIB environment variable
      the perl -Idir command line flag
      the use lib pragma, as in
          use lib "$ENV{HOME}/myown_perllib";

  The latter is particularly useful because it knows about machine
  dependent architectures. The lib.pm pragmatic module was first inclu
+ded
  with the 5.002 release of Perl.
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