Example3_api.kt

data class Credentials(val username: String, val password: String)

interface ContactsApi {
    fun getContacts(credentials: Credentials): Flowable<SimpleContact>

    companion object {
        fun createFor(serverUrl: String) = object: ContactsApi {
            override fun getContacts(credentials: Credentials): 
                    Flowable<SimpleContact> {
                Log.i("ContactsApi",
                        "Querying for contacts from $serverUrl with $credentials")
                return Flowable.just(
                        SimpleContact("Contact1", isStarred = false),
                        SimpleContact("Contact2", isStarred = false),
                        SimpleContact("Contact3", isStarred = true)
                )
            }
        }
    }
}