buildmimetree.py: provide a default visitor_fn (debug)

diff --git a/.config/neomutt/buildmimetree.py b/.config/neomutt/buildmimetree.py
index e2a23a741bbee012d1fd42c6eecf3fbc5fcef7e6..4ab7a5488055c624baee9b91f8ba8fd63b664fa6 100755 (executable)
--- a/.config/neomutt/buildmimetree.py
+++ b/.config/neomutt/buildmimetree.py
@@ -339,9 +339,12 @@ def convert_markdown_to_html(
 
 class MIMETreeDFWalker:
     def __init__(self, *, visitor_fn=None, debug=False):
-        self._visitor_fn = visitor_fn
+        self._visitor_fn = visitor_fn or self._echovisit
         self._debug = debug
 
+    def _echovisit(self, node, ancestry, debugprint):
+        debugprint(f"node={node} ancestry={ancestry}")
+
     def walk(self, root, *, visitor_fn=None):
         """
         Recursive function to implement a depth-dirst walk of the MIME-tree