diff --git a/examples/detector.py b/examples/detector.py
new file mode 100644
index 0000000..06a7a62
--- /dev/null
+++ b/examples/detector.py
@@ -0,0 +1,52 @@
+from typing import TypedDict
+
+from snanosm.mealy import Machine, TransitionInputEnum
+
+
+class Context(TypedDict):
+    count: int
+    position: int
+    matches: int
+
+
+def dinc(context: Context):
+    context["count"] += 1
+
+def dset(context: Context):
+    context["position"] = context["count"]
+    context["count"] += 1
+
+def dprn(context: Context):
+    context["count"] += 1
+    print(f"SUBSTRING FOUND AT POSITION: {context['position']}")
+    context["matches"] += 1
+
+
+# Detects the sequence AB in the string, printing the position and returning the amount of matches
+def detector(input_string: str) -> int:
+    initial_context: Context = {
+        "count": 0,
+        "position": 0,
+        "matches": 0,
+    }
+    m = Machine(initial_context)
+    m.add_state("Q0", True, False)
+    m.add_state("Q1", False, False)
+    m.add_transition("A", "Q0", "Q1", lambda context: dset(context))
+    m.add_transition(TransitionInputEnum.MATCH_REST, "Q0", "Q0", lambda context: dinc(context))
+    m.add_transition("B", "Q1", "Q0", lambda context: dprn(context))
+    m.add_transition(TransitionInputEnum.MATCH_REST, "Q1", "Q0", lambda context: dinc(context))
+    for c in input_string:
+        m.process_input(c)
+    return initial_context["matches"]
+
+if __name__ == "__main__":
+    print("== 1 ==")
+    n = detector("AAAAAAABAAAAAB")
+    print(f"Matches: {n}")
+    print("== 2 ==")
+    n = detector("AAAA")
+    print(f"Matches: {n}")
+    print("== 3 ==")
+    n = detector("ABCCBBACAB")
+    print(f"Matches: {n}")
diff --git a/src/snanosm/mealy.py b/src/snanosm/mealy.py
index 35cb985..6ca1794 100644
--- a/src/snanosm/mealy.py
+++ b/src/snanosm/mealy.py
@@ -32,7 +32,7 @@ class State:
 
 class Transition(Generic[TransitionInput]):
     def __init__(self, transition_input: TransitionInput, origin_name: str, destination_name: str,
-                 output_function: Callable[[Optional[object]], None]) -> None:
+                 output_function: Optional[Callable[[Optional[object]], None]]) -> None:
         self.__transition_input = transition_input
         self.__origin_name = origin_name
         self.__destination_name = destination_name
@@ -40,7 +40,8 @@ class Transition(Generic[TransitionInput]):
         self.__output_function = output_function
 
     def execute_output(self, context):
-        self.__output_function(context)
+        if self.__output_function is not None:
+            self.__output_function(context)
 
     def get_destination_name_hash(self) -> int:
         return self.__destination_name_hash
@@ -63,7 +64,7 @@ class Machine(Generic[Input]):
         self.__context = initial_context
 
     def add_transition(self, transition_input: TransitionInput, origin_name: str, destination_name: str,
-                       output_function: Callable[[Optional[object]], None]) -> None:
+                       output_function: Optional[Callable[[Optional[object]], None]]) -> None:
         ho = hash(origin_name)
         if ho not in self.__states.keys():
             raise ValueError(f"Origin state {origin_name} does not exist.")