#file shared1.pm:
use strict;
sub xxx1 ($\%\@@) # define xxx1 with prototype
{ blah blah;
  return ...;
} # end sub xxx1

use Exporter(); @ISA=qw(Exporter);
@EXPORT = qw(xxx1);   # exports name xxx1 

##</code><code>##

use strict;
use shared1;  # 'include' shared code

...
# call sub defined in shared1.pm
my $result = xxx1($arg1, %arg2, @arg3, $optarg1, $optarg2);
...