> You can't A(B()) if B returns two values.
You can if A is a function which takes two arguments, e.g.
package main
import "log"
func A(x, y int) { log.Printf("%d, %d", x, y) }
func B() (int, int) { return 1, 2 }
func main() { A(B()) }
https://go.dev/play/p/Jp4B0L6NJj2