fixup! Use set instead of list for block level elements

Author: pawamoy

markdown/core.py

@@ -113,7 +113,6 @@ def __init__(self, **kwargs):
         ]
         """ List of characters which get the backslash escape treatment. """
 
-
         # `BLOCK_LEVEL_ELEMENTS` is actually a hybrid list/set container.
         # It supports list methods for backwards compatibility.
         # We expliclitly lie here, so that users running type checkers will get

tests/test_block_level_elements.py

@@ -467,4 +467,4 @@ def test_update(self):
         ble = _BlockLevelElements(["a", "b"])
         ble.update({"b", "c"})
         self.assertEqual(ble._list, ["a", "b", "c"])
-        self.assertEqual(ble._set, {"a", "b", "c"})
+        self.assertEqual(ble._set, {"a", "b", "c"})