fails:String.try_convert returns the argument if it's a String
fails:String.try_convert returns the argument if it's a kind of String
fails:String.try_convert returns nil when the argument does not respond to #to_str
fails:String.try_convert sends #to_str to the argument and returns the result if it's nil
fails:String.try_convert sends #to_str to the argument and returns the result if it's a String
fails:String.try_convert sends #to_str to the argument and returns the result if it's a kind of String
fails:String.try_convert sends #to_str to the argument and raises TypeError if it's not a kind of String
fails:String.try_convert does not rescue exceptions raised by #to_str
