use strict;
use warnings;
use Switch;

package SES;

sub call_ses {
    my ($paramHash, $optHash) = @_;

    print "$_ $paramHash->{$_}\n" for keys %$paramHash;
    return 400, '';
}

package main;

my %params = (hello => "world");
my %opts;
my ($response_code, $response_content) = SES::call_ses \%params, \%opts;

switch() {
    case '400' {}
}