"sudo apt-get install nasm" produces the error message shown in the title, yet it is shown the devel section of xenial (16.04). Any ideas would be greatly appreciated.
(For what it's worth, "sudo apt-get install python-dev" works as you would expect it to.)
nasmis in universe from 16.04 onwards: http://packages.ubuntu.com/search?keywords=nasm. Enable universe. – muru Mar 13 '17 at 06:18