Can you use heredocuments to embed AWK in a bash script?

Writing a shell script that pretty much wraps around an Awk script. I'd like to have my syntax colouring on in the awk section so I feel there must be a better way to embed awk scripts to bash than just quote the script in.

Or is it the best way to develop the awk on a separate file and use awk -f in the bash script until the script's done? I'd like to keep within one file all times!

#!/bin/bash
awkscript='
BEGIN{
    print "test"
}
{print $3}'
df | awk "$awkscript"

This is the quote way, and quite ugly if you ask me. Any chance for heredocs here?