fails:Module#attr creates a getter for the given attribute name
fails:Module#attr creates a setter for the given attribute name if writable is true
fails:Module#attr creates a getter and setter for the given attribute name if called with and without writeable is true
fails:Module#attr applies current visibility to methods created
fails:Module#attr creates a getter but no setter for all given attribute names
fails:Module#attr converts non string/symbol/fixnum names to strings using to_str
fails:Module#attr raises a TypeError when the given names can't be converted to strings using to_str
fails:Module#attr is a private method
