Is it bad form to put code in package.d other than imports?

[Soulsbane via Digitalmars-d-learn]

I've only understood that imports should go in package.d. I'm 
seeing more and more packages on code.dlang.org using it for the 
packages primary code. Is this alright? As far as I can tell it's 
just bad form. It would be nice to have one of the maintainers 
higher up the food chain comment on this!

Thanks!