fix incompatibility for python <3.9

nicegui/elements/choice_element.py

@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, Literal, Optional, Union
+from typing import Any, Callable, Dict, List, Optional, Union
 
 import justpy as jp
 
@@ -21,7 +21,7 @@ class ChoiceElement(ValueElement):
         except ValueError:
             return value
 
-    def handle_change(self, msg: Dict) -> Literal[False]:
+    def handle_change(self, msg: Dict):
         index = msg['value']['value'] if isinstance(msg['value'], dict) else msg['value']
         msg['index'] = index
         msg['label'] = self.labels[index]

nicegui/elements/value_element.py

@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, Literal, Optional
+from typing import Any, Callable, Dict, Optional
 
 import justpy as jp
 
@@ -25,7 +25,7 @@ class ValueElement(Element):
     def set_value(self, value) -> None:
         self.value = value
 
-    def handle_change(self, msg: Dict) -> Literal[False]:
+    def handle_change(self, msg: Dict):
         self.value = msg['value']
         self.update()
         return False