join
inline fun <I, R> Iterable<I>.joinTo(separatorFun: (I) -> R?, prefix: R? = null, postfix: R? = null, transform: (I) -> R?): List<R>
inline fun <I, R> Iterable<I>.joinTo(separator: R? = null, prefix: R? = null, postfix: R? = null, transform: (I) -> R?): List<R>
inline fun <I> Iterable<I>.joinTo(separatorFun: (I) -> I?, prefix: I? = null, postfix: I? = null): List<I>
inline fun <I> Iterable<I>.joinTo(separator: I? = null, prefix: I? = null, postfix: I? = null): List<I>