在包的init函数中初始化变量是否可以确保golang应用中的单个实例？

I am writing a Bloom Filter package. Within my package, I want to create an instance of X (non-exported) which I want to exist only as a single instance; no matter how many times my package is imported into an app.

A simple snippet of what I am doing is:

package superduperbloomfilter

var x X

func init() {
    x = X.New(....)
}

Is this correct ?

which I want to exist only as a single instance; no matter how many times my package is imported into an app

The spec says an imported package is initialized only once:

If a package has imports, the imported packages are initialized before initializing the package itself. If multiple packages import a package P, P will be initialized only once.