add decorator for cli context

tests/test_decorator.py

@@ -0,0 +1,10 @@
+import ast
+
+from dbyaml.decorator import attribute_path
+
+tree = ast.parse("alpha.beta().gamma").body[0].value  # ty: ignore[unresolved-attribute]
+
+
+def test_attribute_path():
+  path = attribute_path(tree)
+  assert path == ["alpha", "beta()", "gamma"]