how to install fasm in fedora
The package built for F30 should normally work on a F31 as well: https://fedora.pkgs.org/30/rpm-sphere-x86_64/fasm-1.73.16-1.x86_64.rpm.html (includes instructions) - be aware, this is all third party software, not gone through Fedora’s review and QA.
Otherwise you can get it from flat assembler