fails:Symbol#swapcase returns a Symbol
fails:Symbol#swapcase converts lowercase ASCII characters to their uppercase equivalents
fails:Symbol#swapcase converts uppercase ASCII characters to their lowercase equivalents
fails:Symbol#swapcase works with both upper- and lowercase ASCII characters in the same Symbol
fails:Symbol#swapcase leaves uppercase Unicode characters as they were
fails:Symbol#swapcase leaves lowercase Unicode characters as they were
fails:Symbol#swapcase leaves non-alphabetic ASCII characters as they were
