Clarified forwarding of events.

Sources/Observer.swift

@@ -45,6 +45,11 @@ public struct Observer<Value, Error: ErrorProtocol> {
         }
     }
     
+    
+    public func sendEvent(_ event: Event<Value, Error>) {
+        action(event)
+    }
+    
     /// Puts a `Next` event into the given observer.
     public func sendNext(_ value: Value) {
         action(.Next(value))

Sources/Signal.swift

@@ -248,7 +248,7 @@ extension SignalType {
     public func map<U>(transform: (Value) -> U) -> Signal<U, Error> {
         return Signal { observer in
             return self.on { event -> Void in
-                observer.action(event.map(transform))
+                observer.sendEvent(event.map(transform))
             }
         }
     }
@@ -258,7 +258,7 @@ extension SignalType {
     public func mapError<F>(transform: (Error) -> F) -> Signal<Value, F> {
         return Signal { observer in
             return self.on { event -> Void in
-                observer.action(event.mapError(transform))
+                observer.sendEvent(event.mapError(transform))
             }
         }
     }
@@ -269,7 +269,7 @@ extension SignalType {
         return Signal { observer in
             return self.on { (event: Event<Value, Error>) -> Void in
                 guard let value = event.value else {
-                    observer.action(event)
+                    observer.sendEvent(event)
                     return
                 }