Like what? The standard library is no more special, other than where it resides in the filesystem. You can write C and assembly code as well and link it to your Go code. And I'm not talking about cgo, I mean [568][ac], the Plan 9 C compiler and assembler that come with Go.
I was thinking most obviously of generics. The go standard library is full of generic collections, but you're not allowed to use generics in your own code.
