core (constants): type hints

sat/core/constants.py

@@ -425,7 +425,7 @@ class Const(object):
         )
 
     @classmethod
-    def bool(cls, value):
+    def bool(cls, value: str) -> bool:
         """@return (bool): bool value for associated constant"""
         assert isinstance(value, str)
         return value.lower() in (cls.BOOL_TRUE, "1", "yes", "on")