#! /usr/bin/perl
use warnings;
use strict;

use String::Interpolate;

my $template = 'String::Interpolate'->new;
$template->('http://something.com/api_stuff/$GUID');

make_call( '1234' );

sub make_call {
    my $GUID = shift;
    $template->{GUID} = $GUID;
    POST("$template");
}

use Test::More;
sub POST {
    is shift, 'http://something.com/api_stuff/1234', 'intepolates';
}

done_testing();