in reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/LogicalState.kt [49:56]
override fun addReactivatable(logical: Logical<*>, reactivatable: Reactivatable) {
if (!observers.containsKey(logical)) {
logical.addObserver(this)
}
val list = observers.getOrPut(logical) { arrayListOf() }
// TODO this check may be inefficient, but it's necessary
if (!list.contains(reactivatable)) list.add(reactivatable)
}