with an 'expect 10', chapter one of mysterylang is written

grammar.y

@@ -24,8 +24,14 @@ prechigh
   left     ':'
   right    '-=' '+=' '/=' '*=' '||=' '&&='
   nonassoc IF
+  left     UNLESS
+  right    RETURN THROW FOR WHILE
 preclow
 
+# We expect 10 shift/reduce errors for optional syntax.
+# There used to be 252 -- greatly improved.
+expect 10
+
 rule
 
   # All parsing will end in this rule, being the trunk of the AST.