func foo() []int {
	return nil
}

func foo1() map[int]int {
	return make(map[int]int, 10)
}

func foo2() chan int {
	return make(chan int, 10)
}

func foo3() *int {
	return nil
}

println(foo() == nil)
println(nil == foo())
println(foo() != nil)
println(nil != foo())

println(foo1() == nil)
println(nil == foo1())
println(foo1() != nil)
println(nil != foo1())

println(foo2() == nil)
println(nil == foo2())
println(foo2() != nil)
println(nil != foo2())

println(foo3() == nil)
println(nil == foo3())
println(foo3() != nil)
println(nil != foo3())