feat: adding circuit breaker feature

Author: leandrodamascena

docs/utilities/circuit_breaker.md

@@ -149,10 +149,10 @@ Register an `on_circuit_open` callback to decide what happens to a rejected requ
 
 If no callback is registered, an open circuit raises `CircuitBreakerOpenError`. Catch it to decide how to respond. The exception carries a `circuit` attribute (`CircuitInfo`) so you can inspect why the request was rejected.
 
-=== "working_with_custom_config.py"
+=== "working_without_callback.py"
 
     ```python hl_lines="5 16-22 38-43"
-    --8<-- "examples/circuit_breaker_alpha/src/working_with_custom_config.py"
+    --8<-- "examples/circuit_breaker_alpha/src/working_without_callback.py"
     ```
 
 ## Configuration

examples/circuit_breaker_alpha/src/getting_started_with_circuit_breaker.py

@@ -11,7 +11,7 @@
 
 
 class PaymentBackend:
-    def charge(self, order: dict) -> dict: ...
+    def charge(self, order: dict): ...
 
 
 payment_api = PaymentBackend()

examples/circuit_breaker_alpha/src/working_with_callback.py

@@ -16,7 +16,7 @@
 
 
 class PaymentBackend:
-    def charge(self, order: dict) -> dict: ...
+    def charge(self, order: dict): ...
 
 
 payment_api = PaymentBackend()

examples/circuit_breaker_alpha/src/working_with_metrics.py

@@ -26,7 +26,7 @@ def emit_transition_metric(transition: CircuitTransition) -> None:
 
 
 class PaymentBackend:
-    def charge(self, order: dict) -> dict: ...
+    def charge(self, order: dict): ...
 
 
 payment_api = PaymentBackend()

…_alpha/src/working_with_custom_config.py …er_alpha/src/working_without_callback.pyexamples/circuit_breaker_alpha/src/working_with_custom_config.py renamed to examples/circuit_breaker_alpha/src/working_without_callback.py examples/circuit_breaker_alpha/src/working_with_custom_config.py renamed to examples/circuit_breaker_alpha/src/working_without_callback.py

@@ -24,7 +24,7 @@
 
 
 class PaymentBackend:
-    def charge(self, order: dict) -> dict: ...
+    def charge(self, order: dict): ...
 
 
 payment_api = PaymentBackend()
@@ -40,4 +40,5 @@ def lambda_handler(event: dict, context: LambdaContext):
         return charge(event)
     except CircuitBreakerOpenError as exc:
         # No callback registered, so we decide what to do with the rejected request here.
-        return {"statusCode": 202, "circuit": exc.circuit.name}
+        circuit_name = exc.circuit.name if exc.circuit else "unknown"
+        return {"statusCode": 202, "circuit": circuit_name}