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python/dgl/sparse/sparse_matrix.py

@@ -576,7 +576,9 @@ def range_select(self, dim: int, index: slice):
             raise ValueError("The selection dimension should be 0 or 1.")
         if isinstance(index, slice):
             if index.step not in (None, 1):
-                raise NotImplementedError
+                raise NotImplementedError(
+                    "Slice with step other than 1 are not supported yet."
+                )
             start = 0 if index.start is None else index.start
             end = index.stop
             return SparseMatrix(