(start with a <code> tag, of course, or just <c>)
# your sample code
# goes here… (but please just include what you're actually using)

# when it's time to read the sample data in your code, do this:
while (<DATA>) {
    # do stuff with the sample data
}

# more code… enough to exit cleanly with coherent output…

__DATA__
your sample data
goes here…
(don't forget the closing "code" tag…)