stdlib/builtin/symbol.rbs in rbs-0.14.0 vs stdlib/builtin/symbol.rbs in rbs-0.15.0

@@ -107,10 +107,10 @@
   # `other_symbol` is not a symbol.
   #
   #     :foo.casecmp?(2)   #=> nil
   #     "\u{e4 f6 fc}".encode("ISO-8859-1").to_sym.casecmp?(:"\u{c4 d6 dc}")   #=> nil
   #
-  def casecmp?: (untyped other) -> bool
+  def casecmp?: (untyped other) -> bool?
 
   # Same as `sym.to_s.downcase.intern`.
   #
   def downcase: () -> Symbol
               | (:ascii | :fold | :lithuanian | :turkic) -> Symbol