How do I solve this mixed enum equatable thing?

Question

I have this

enum MyEnum {
  case one
  case two
}

and this

var array:[MyEnum] = [.one]

and later

func add(_ case:MyEnum) {
  if array.contains(case) { return }
  array.append(case)
}

So far so good.

Then I have added a third option to the enum

enum MyEnum {
  case one
  case two
  case three(user:User)
}

then the line

if array.contains(case) { return }

is giving this error

Referencing instance method 'contains' on 'Sequence' requires that 'MyEnum' conform to 'Equatable'

I guess that the problem is this

1. contains can easily see if .one is equal to .two or not, so it can check if these elements are on array.
2. contains cannot easily see if .three(user:"bob") is the same as .three(user:"carl"), right?

I don't care which user is, I just want to compare if array has an entry three or not.

If the array is [.two, .one, .three(user:"bob)] and I try to append .three("user:"carl") I want the line if array.contains(.three("user:"carl"))to return true.

How do I do that?