Sample class to demonstrate usage of `tryOptional` in Kotlin. See: https://gist.github.com/raxityo/8a109787966abc38c27b5620ce93b225

TokenGenerator.kt

class TokenGenerator {

    private var canObtainToken = true
    private var token = "TOKEN"

    fun obtainToken(): String {
        if (!canObtainToken) {
            throw Error()
        }

        canObtainToken = false
        return token
    }

    fun returnToken() {
        canObtainToken = true
    }
}

val tokenGenerator = TokenGenerator()
println(tokenGenerator.obtainToken()) // Prints: TOKEN

val anotherToken = tryOptional { tokenGenerator.obtainToken() }
println(anotherToken) // Prints: null

// Optional chaining.
// Prints: NULL TOKEN
tryOptional {
    tokenGenerator.obtainToken()
}?.let {
    println(it)
} ?: println("null TOKEN")