如何在go中引用未命名的函数参数？

The name of a function parameter in go is optional. meaning the following is legal

func hello(string) {

    fmt.Println("Hello")
}

func main() {
    hello("there")
}

(Go Playground link)

How can I refer to the 1. argument (declared with a type of string) argument in the foo() function ?

The only use of unnamed parameters is when you have to define a function with a specific signature. For instance, I have this example in one of my projects:

type export struct {
    f func(time.Time, time.Time, string) (interface{}, error)
    folder    string
}

And I can use both of these functions in it:

func ExportEvents(from, to time.Time, name string) (interface{}, error)
func ExportContacts(from, to time.Time, _ string) (interface{}, error)

Even though in the case of ExportContacts, I do not use the string parameter. In fact, without naming this parameter, I have no way of using it in this function.