Is unnamed arguments a thing in Go?

I am writing a parser in Go for Go, and to test it I downloaded a bunch of files from github projects.
In I bumped into a file containing this piece of code:

func moveLabel(*Button) {
    from := movingCurrent
    to := 0
    if from == 0 {
        to = 1
    movingBoxes[to].Append(movingLabel, false)
    movingCurrent = to

It confuse me a bit to see a pointer to a Button without a name as a function argument, which makes it impossible to reference from inside the function.
However, it seems to be syntactically correct given that the compiler doesn’t complains.
What is the purpose of unamed functions arguments in Go?