fixed literals for result types

Author: Dpbm

example_plugin/interface.py

@@ -4,13 +4,13 @@
 
 from abc import ABC, abstractmethod
 import os
-from typing import List, Dict, Any
+from typing import List, Dict, Any, Literal
 from .config import AVAILABLE_RESULT_TYPES
 
 Backend = str
 Backends = List[Backend]
 Metadata = Dict[Any, Any]
-ResultType = str
+ResultType = Literal['counts', 'quasi_dist', 'expval']
 QasmFilePath = str
 Results = Dict[str | int, float] | List[float]