diff --git a/src/polluck_blockchain/placeholder_native.pyx b/src/polluck_blockchain/placeholder_native.pyx
index d95a402..0f12a00 100644
--- a/src/polluck_blockchain/placeholder_native.pyx
+++ b/src/polluck_blockchain/placeholder_native.pyx
@@ -164,6 +164,8 @@ cdef class Blockchain:
     def __init__(self, *args, **kwargs):
         pass
     
+    # TODO add entries of map
+    # ownership is typically not transferred from the Blockchain extension class
     def __dealloc__(self):
         if self._chain is not NULL:
             del self._chain