#!/usr/bin/awk -f
BEGIN { in_code_block = 0 }
/^```/ {
    if (!in_code_block) {
        in_code_block = 1;
        first_line = 1;
    } else {
        in_code_block = 0;
        print "";
    }
}
{
    if (in_code_block && !first_line) {
        print;
    }
    first_line = 0;
}