kotlin-stdlib / kotlin.sequences / singleOrNull singleOrNull Common JVM JS Native 1.0 fun <T> Sequence<T>.singleOrNull(): T?(source) Returns single element, or null if the sequence is empty or has more than one element. The operation is terminal. Common JVM JS Native 1.0 inline fun <T> Sequence<T>.singleOrNull( predicate: (T) -> Boolean): T?(source) Returns the single element matching the given predicate, or null if element was not found or more than one element was found. The operation is terminal.