Is it possible to set the value of a variable as a span tag via //dd:span?

[your-diary]

According to the official documentation, one can manually create a span via a //dd:span comment:

//dd:span custom_tag:tag_value
func CriticalPathFunction() {
  // ... implementation details ...
}

I expected tag_value in custom_tag:tag_value would be replaced by the value of tag_value variable defined in the function body, but actually it turned out it was literally interpreted.

So, in my case,

//dd:span user_id:userID ret:ret
func repository(userID string) (ret string) {
	ret = "Mike"
	return
}

gives this result:

Is it possible to set the value of a variable (e.g. function paremeters) as a span tag?