fun <T> Iterable<T>.noneOrSingle(predicate: (T) -> Boolean): T?
Returns the single element matching the given predicate, or null
if element was not found,
or throws if more than one element was found.
fun <T> Iterable<T>.noneOrSingle(): T?
Returns single element, or null
if element was not found, or throws if more than one element was found.