Update code examples

source/_cookbook/python_component_mqtt_basic.markdown

@@ -21,10 +21,10 @@ This example follows a topic on MQTT and updates the state of an entity to the l
 ```python
 import homeassistant.loader as loader
 
-# The domain of your component. Should be equal to the name of your component
+# The domain of your component. Should be equal to the name of your component.
 DOMAIN = "hello_mqtt"
 
-# List of component names (string) your component depends upon
+# List of component names (string) your component depends upon.
 DEPENDENCIES = ['mqtt']
 
 
@@ -33,31 +33,31 @@ DEFAULT_TOPIC = 'home-assistant/hello_mqtt'
 
 
 def setup(hass, config):
-    """ Setup our hello_mqtt component. """
+    """Setup the Hello MQTT component."""
     mqtt = loader.get_component('mqtt')
     topic = config[DOMAIN].get('topic', DEFAULT_TOPIC)
     entity_id = 'hello_mqtt.last_message'
 
-    # Listener to be called when we receive a message
+    # Listener to be called when we receive a message.
     def message_received(topic, payload, qos):
-        """ A new MQTT message has been received. """
+        """A new MQTT message has been received."""
         hass.states.set(entity_id, payload)
 
-    # Subscribe our listener to a topic
+    # Subscribe our listener to a topic.
     mqtt.subscribe(hass, topic, message_received)
 
     # Set the intial state
     hass.states.set(entity_id, 'No messages')
 
-    # Service to publish a message on MQTT
+    # Service to publish a message on MQTT.
     def set_state_service(call):
-        """ Service to send a message. """
+        """Service to send a message."""
         mqtt.publish(hass, topic, call.data.get('new_state'))
 
-    # Register our service with Home Assistant
+    # Register our service with Home Assistant.
     hass.services.register(DOMAIN, 'set_state', set_state_service)
 
-    # return boolean to indicate that initialization was successful
+    # Return boolean to indicate that initialization was successfully.
     return True
 ```