Comment example.

examples/state_machine.py

@@ -16,29 +16,45 @@ dp = Dispatcher(bot)
 
 @dp.message_handler(commands=['start'])
 async def send_welcome(message: types.Message):
+    """
+    Entry point to conversation 
+    """
     await message.reply("Hi there! What's your name?")
+
+    # Set state
+    # This method lock all messages from user and all messages will be redirected to next step handler in state machine
     state.set_state(message.chat.id, message.from_user.id, "name")
 
 
 async def process_name(message, controller):
+    """
+    Process user name
+    """
+    # Save name to storage
     controller["name"] = message.text
 
     await message.reply("How old are you?")
 
+    # Go to next state
     controller.set_state('age')
 
 
 async def process_age(message, controller):
+    # Check age. Age must be is digit
     if not message.text.isdigit():
         return await message.reply("Age should be a number.\nHow old are you?")
 
+    # Save age to storage
     controller["age"] = int(message.text)
 
+    # Configure ReplyKeyboardMarkup
     markup = types.ReplyKeyboardMarkup()
     markup.add("Male", "Female")
     markup.add("Other")
+
     await message.reply("What is your gender?", reply_markup=markup)
 
+    # Go to next state
     controller.set_state("sex")
 
 
@@ -46,8 +62,10 @@ async def process_sex(message, controller):
     if message.text not in ["Male", "Female", "Other"]:
         return await message.reply("Bad gender name. Choose you gender from keyboard.")
 
+    # Save sex to storage
     controller["sex"] = message.text
 
+    # Remove keyboard
     markup = types.ReplyKeyboardRemove()
     await bot.send_message(message.chat.id,
                            f"Hi!\n"
@@ -55,9 +73,12 @@ async def process_sex(message, controller):
                            f"Age: {controller['age']}\n"
                            f"Sex: {controller['sex']}",
                            reply_markup=markup)
+
+    # Finish conversation
     controller.clear()
 
 
+# Configure state machine
 state = StateMachine(dp, {
     "name": process_name,
     "age": process_age,