def to_xml(dest = :string, options = {})
      dest = XML::Writer.new(dest, options) unless dest.is_a?(XML::Writer)
      Mapper.of(self.class).write(self, dest)
      dest.result
    end
def to_xml(dest = :string, options = {})
      dest = XML::Writer.new(dest, options) unless dest.is_a?(XML::Writer)
      Mapper.of(self.class).write(self, dest)
      dest.result
    end
save_to(:string|:document[, options])      -> new_string|new_document
    save_to(string|iolike|document[, options]) -> string|iolike|document

 Defines attribute mapping.

 [+options+] Backend-specific options

 === Example:
    cat = Cat.new
    cat.name = 'Pussy'
    puts cat.save_to(:string)
    ...
    doc = LibXML::XML::Document.new
    cat.save_to(doc)
    puts doc.to_s