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collections.py

@@ -1,21 +1,24 @@
-from abc import abstractmethod
+import typing
 from dataclasses import field
+from typing import Dict, List
 
 from .artifact import Artifact
+from .dataclass import AbstractField
 from .random_utils import random
 
 
 class Collection(Artifact):
-    @abstractmethod
+    items: typing.Collection = AbstractField()
+
     def __getitem__(self, key):
-        pass
+        try:
+            return self.items[key]
+        except LookupError:
+            raise LookupError(f"Cannot find item {repr(key)} in {repr(self)}")
 
 
 class ListCollection(Collection):
-    items: list = field(default_factory=list)
-
-    def __getitem__(self, index):
-        return self.items[index]
+    items: List[Artifact] = field(default_factory=list)
 
     def __len__(self):
         return len(self.items)
@@ -31,10 +34,7 @@ class ListCollection(Collection):
 
 
 class DictCollection(Collection):
-    items: dict = field(default_factory=dict)
-
-    def __getitem__(self, key):
-        return self.items[key]
+    items: Dict[str, Artifact] = field(default_factory=dict)
 
 
 class ItemPicker(Artifact):