my $source = DateTime->new(
    year      => 1998, month  => 4, day => 7,
    hour      => 13,   minute => 55,
    time_zone => 'America/New_York'
);
my $result = $source->clone()->set_time_zone('America/Los_Angeles');
print $source->strftime("%F %r %Z"), " became ",
    $result->strftime("%F %r %Z");

# Prints: 1998-04-07 01:55:00 PM EDT became 1998-04-07 10:55:00 AM PDT