Rules of a subscription have been added

Combine.playground/Pages/Rules of subscriptions.xcplaygroundpage/Contents.swift

@@ -1,8 +1,36 @@
 /*:
  [Previous](@previous)
  ## The rules of a subscription
- - There can only be _one_ subscriber
+ - A subscriber will receive a _single_ subscription
  - _Zero_ or _more_ values can be published
  - At most _one_ completion will be called
  */
+import Combine
+import UIKit
+
+enum ExampleError: Swift.Error {
+    case somethingWentWrong
+}
+
+let subject = PassthroughSubject<String, ExampleError>()
+
+//let publisher = Publisher<String, ExampleError>(subject: subject)
+subject.handleEvents(receiveSubscription: { (subscription) in
+    print("New subscription!")
+}, receiveOutput: { _ in
+    print("Received new value!")
+}, receiveCompletion: { _ in
+    print("A subscription completed")
+}, receiveCancel: {
+    print("A subscription cancelled")
+}).sink { (value) in
+    print("Subscriber one received value: \(value)")
+}
+
+subject.send("Hello!")
+subject.send("Hello again!")
+subject.send("Hello for the last time!")
+subject.send(completion: Subscribers.Completion<ExampleError>.failure(ExampleError.somethingWentWrong))
+subject.send("Hello?? :(")
+
 //: [Next](@next)

Combine.playground/contents.xcplayground

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='6.0' target-platform='ios' display-mode='rendered'>
+<playground version='6.0' target-platform='ios' display-mode='raw'>
     <pages>
         <page name='What is Combine'/>
         <page name='Publishers &amp; Subscribers'/>