minimize diff

flox/core.py

@@ -514,7 +514,7 @@ def invert(x) -> tuple[np.ndarray, ...]:
         ]
         cohort_ = present_labels[cohidx]
         cohort = [elem.item() for elem in cohort_ if elem not in merged_keys]
-        if len(cohort) == 0:
+        if not cohort:
             continue
         merged_keys.update(cohort)
         allchunks = (label_chunks[member].tolist() for member in cohort)