toSet
Platform and version requirements: JVM (1.0), JS (1.0), Native (1.0) 
fun <T> Sequence<T>.toSet(): Set<T>
Returns a Set of all elements.
The returned set preserves the element iteration order of the original sequence.
The operation is terminal.
    © 2010–2020 JetBrains s.r.o. and Kotlin Programming Language contributors
Licensed under the Apache License, Version 2.0.
    https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.sequences/to-set.html