Just do a naive lookup for symbol normalization

piker/brokers/kraken/api.py

@@ -450,11 +450,13 @@ def normalize_symbol(
     Normalize symbol names to to a 3x3 pair.
 
     '''
+    remap = {
+        'XXBTZEUR': 'XBTEUR',
+        'XXMRZEUR': 'XMREUR',
+    }
     symlen = len(ticker)
     if symlen != 6:
-        for sym in ['XXBT', 'XXMR', 'ZEUR']:
-            if sym in ticker:
-                ticker = ticker.replace(sym, sym[1:])
+        ticker = remap[ticker]
     else:
         raise ValueError(f'Unhandled symbol: {ticker}')