How to create lib in app?

Question

go

How to create a library for an application?
For example, the user.go functions should be in lib and called through: Implementation through packages is not suitable. Because the library becomes completely global and loses the scope of the standard functions. Just like that from src/app/user.go, I can't put in src/app/lib/user.go. Because there are problems when compiling, in other words, it does not see the lib directory
type User struct{}
go build