update demo

csst_proto/demo.py

@@ -66,9 +66,10 @@ class DemoClass:
     >>> a.say_hello()
     """
 
-    def __init__(self, first_name, last_name) -> None:
+    def __init__(self, first_name: str, last_name: str) -> None:
         self.first_name = first_name
         self.last_name = last_name
 
     def say_hello(self) -> None:
+        """111"""
         print("Hello, {} {}!".format(self.first_name, self.last_name))