upgrade

src/skill_tree/exercises/markdown.py

@@ -3,7 +3,7 @@ import sys
 from parsec import one, eof
 from parsec.combinator import *
 from parsec.text import *
-from .market_math import processor
+from .marked_math import processor
 
 """
 使用 markdown 编写的问题应该总是一个固定格式，即

src/test/exercises/markdown_test.py

@@ -2,7 +2,7 @@ import unittest
 
 from parsec.state import BasicState
 
-from skill_tree.exercises.market_math import processor
+from skill_tree.exercises.marked_math import processor
 import skill_tree.exercises.markdown as mk