Index: gc_core/py/lang_core/gc_engine.py
==================================================================
--- gc_core/py/lang_core/gc_engine.py
+++ gc_core/py/lang_core/gc_engine.py
@@ -901,20 +901,27 @@
             if nTokenRewriteEnd - nTokenRewriteStart == 0:
                 self.lToken[nTokenRewriteStart]["bToRemove"] = True
             else:
                 for i in range(nTokenRewriteStart, nTokenRewriteEnd+1):
                     self.lToken[i]["bToRemove"] = True
-        elif sWhat == "_":
+        elif sWhat == "=":
             # merge tokens
             self.lToken[nTokenRewriteStart]["nMergeUntil"] = nTokenRewriteEnd
         elif sWhat == "!":
             # immunity
             if nTokenRewriteEnd - nTokenRewriteStart == 0:
                 self.lToken[nTokenRewriteStart]["bImmune"] = True
             else:
                 for i in range(nTokenRewriteStart, nTokenRewriteEnd+1):
                     self.lToken[i]["bImmune"] = True
+        elif sWhat == "_":
+            # neutralized token
+            if nTokenRewriteEnd - nTokenRewriteStart == 0:
+                self.lToken[nTokenRewriteStart]["sNewValue"] = "_"
+            else:
+                for i in range(nTokenRewriteStart, nTokenRewriteEnd+1):
+                    self.lToken[i]["sNewValue"] = "_"
         else:
             if sWhat.startswith("="):
                 sWhat = globals()[sWhat[1:]](self.lToken)
             bUppercase = bUppercase and self.lToken[nTokenRewriteStart]["sValue"][0:1].isupper()
             if nTokenRewriteEnd - nTokenRewriteStart == 0: