abstract fun add(element: E): Boolean
Overrides MutableSet.add
Adds the specified element to the set.
This method is redeclared as abstract, because it's not implemented in the base class, so it must be always overridden in the concrete mutable collection implementation.
Return true if the element has been added, false if the element is already contained in the set.
© 2010–2018 JetBrains s.r.o.
Licensed under the Apache License, Version 2.0.
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-abstract-mutable-set/add.html