A.swift

class A {
    /// The instance of B we are using to check if we have the answer.
    var b: B?
    /// A `Bool` indicating if we have the answer to the universe.
    private(set) var hasAnswer = false

    /// Checks if we have the answer to the universe and updates the `hasAnswer` property.
    func checkAnswer() {
        hasAnswer = b?.validateAnswer() ?? false
    }
}