diff --git a/examples/hello-world/src/hello_world/stateful_stream.clj b/examples/hello-world/src/hello_world/stateful_stream.clj
index dea329a..ed5b7db 100644
--- a/examples/hello-world/src/hello_world/stateful_stream.clj
+++ b/examples/hello-world/src/hello_world/stateful_stream.clj
@@ -1,9 +1,8 @@
 (ns hello-world.stateful-stream
   (:require [re-streamer.stateful-stream :as stateful-stream]))
 
-;; stateful-stream
-
 ;; create stateful stream with initial value
+;; note: if you don't pass it, initial value will be nil
 (def foo (stateful-stream/create 10))
 
 ;; subscribe to the stateful stream
diff --git a/examples/hello-world/src/hello_world/stream.clj b/examples/hello-world/src/hello_world/stream.clj
index e08ced8..dae1718 100644
--- a/examples/hello-world/src/hello_world/stream.clj
+++ b/examples/hello-world/src/hello_world/stream.clj
@@ -1,8 +1,6 @@
 (ns hello-world.stream
   (:require [re-streamer.stream :as stream]))
 
-;; stream
-
 ;; create stream
 (def bar (stream/create))
 
diff --git a/project.clj b/project.clj
index 99322db..e56a9e7 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject org.clojars.stanimirovic/re-streamer "0.2.1"
+(defproject org.clojars.stanimirovic/re-streamer "0.2.2"
   :description "Simple Clojure library for reactive programming"
   :url "https://github.com/stanimirovic/re-streamer"
   :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
diff --git a/src/re_streamer/stateful_stream.cljc b/src/re_streamer/stateful_stream.cljc
index ad160d6..6dc3813 100644
--- a/src/re_streamer/stateful_stream.cljc
+++ b/src/re_streamer/stateful_stream.cljc
@@ -1,6 +1,6 @@
 (ns re-streamer.stateful-stream
   #?(:cljs (:require [reagent.core :as reagent]))
-  (:refer-clojure :rename {map c-map distinct c-distinct}))
+  (:refer-clojure :rename {map c-map distinct c-distinct filter c-filter}))
 
 (defn create
   ([] (create nil))
@@ -28,31 +28,37 @@
 
 ;; operators
 
-(defn map [stream f]
+(defn map [stream f watcher-key]
   (let [state #?(:cljs    (reagent/atom (f @(:state stream)))
                  :default (atom (f @(:state stream))))
         subs (atom #{})]
 
-    (add-watch (:state stream) :watch #(reset! state (f %4)))
+    (add-watch (:state stream) watcher-key #(reset! state (f %4)))
     (add-watch state :watch #(doseq [sub @subs] (sub %4)))
 
-    {:subscribe! (fn [sub]
-                   (swap! subs conj sub)
-                   (sub @state))
-     :state      state}))
+    {:subscribe!   (fn [sub]
+                     (swap! subs conj sub)
+                     (sub @state))
+     :unsubscribe! (fn [sub]
+                     (swap! subs disj sub)
+                     nil)
+     :state        state}))
 
-(defn pluck [stream keys]
-  (map stream #(select-keys % keys)))
+(defn pluck [stream keys watcher-key]
+  (map stream #(select-keys % keys) watcher-key))
 
-(defn distinct [stream f]
+(defn distinct [stream f watcher-key]
   (let [state #?(:cljs    (reagent/atom @(:state stream))
                  :default (atom @(:state stream)))
         subs (atom #{})]
 
-    (add-watch (:state stream) :watch #(if (not (f @state %4)) (reset! state %4)))
+    (add-watch (:state stream) watcher-key #(if (not (f @state %4)) (reset! state %4)))
     (add-watch state :watch #(doseq [sub @subs] (sub %4)))
 
-    {:subscribe! (fn [sub]
-                   (swap! subs conj sub)
-                   (sub @state))
-     :state      state}))
+    {:subscribe!   (fn [sub]
+                     (swap! subs conj sub)
+                     (sub @state))
+     :unsubscribe! (fn [sub]
+                     (swap! subs disj sub)
+                     nil)
+     :state        state}))