Example 1:
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Sample.pl:
----------
#!/usr/bin/perl -w
use strict;
use Zoo;
print $pet, "\n";

Zoo.pm:
-------
package Zoo;
our $pet = "Cat";
sub import {
  my $package = shift;
  my ($callerpkg, $file, $lineno) = caller;
  #################
  # Type-glob below
  #################
  *{"${callerpkg}::pet"} = \${"${package}::pet"};
}
1;

Output:
-------
>./sample.pl
Cat
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Example 2:
=========================
Sample.pl:
----------
#!/usr/bin/perl -w
use strict;
use Zoo;
print $pet, "\n";

Zoo.pm:
-------
package Zoo;
our $pet = "Cat";
sub import {
  my $package = shift;
  my ($callerpkg, $file, $lineno) = caller;
  ####################
  # Symbolic reference below
  ####################
  ${"${callerpkg}::pet"}  = ${"${package}::pet"};
}
1;

Output:
-------
>./sample.pl
Variable "$pet" is not imported at ./sample.pl line 6.
Global symbol "$pet" requires explicit package name at ./sample.pl line 6.
Execution of ./sample.pl aborted due to compilation errors.
=========================