Add missing ABC for Metric
Fix
@@ -87,13 +87,14 @@ class DefaultLabelSet(LabelSet):
"""
-class Metric:
+class Metric(abc.ABC):
"""Base class for various types of metrics.
Metric class that inherit from this class are specialized with the type of
handle that the metric holds.
"""
+ @abc.abstractmethod
def get_handle(self, label_set: LabelSet) -> "object":
"""Gets a handle, used for repeated-use of metrics instruments.
