fails:String#tr can replace a 7-bit ASCII character with a multibyte one
fails:String#tr raises a ArgumentError a descending range in the replacement as containing just the start character
fails:String#tr raises a ArgumentError a descending range in the source as empty
fails:String#tr supports non-injective replacements

fails:String#tr can replace a 7-bit ASCII character with a multibyte one
fails:String#tr supports non-injective replacements

Remove tags for passing specs
Remove tags for passing specs
