Minor API improvement

Author: chrisjsewell

markdown_it/main.py

@@ -53,6 +53,9 @@ def __init__(
         if options:
             self.set(options)
 
+    def __repr__(self):
+        return f"{self.__class__.__module__}.{self.__class__.__name__}()"
+
     def __getitem__(self, name):
         return {
             "inline": self.inline,

markdown_it/token.py

@@ -79,6 +79,10 @@ def attrJoin(self, name, value):
         else:
             self.attrs[idx][1] = self.attrs[idx][1] + " " + value
 
+    def copy(self):
+        """Return a shallow copy of the instance."""
+        return attr.evolve(self)
+
     def as_dict(self, children=True, filter=None, dict_factory=dict):
         """Return the token as a dict.
 
@@ -128,6 +132,7 @@ def nest_tokens(tokens: List[Token]) -> List[Union[Token, NestedTokens]]:
         token = tokens.pop()
 
         if token.nesting == 0:
+            token = token.copy()
             output.append(token)
             if token.children:
                 token.children = nest_tokens(token.children)