def root(local_name = nil, options = {})
      mapper.root = Root.new(local_name, prepare_options(:root, options)) if local_name
      mapper.root
    end
def root(local_name = nil, options = {})
      mapper.root = Root.new(local_name, prepare_options(:root, options)) if local_name
      mapper.root
    end
root(local_name[, :ns => ...]) -> Mappings::Root
    root                           -> Mappings::Root

 Defines element name.
 TODO: moar details

 [+local_name+] Element name
 [+options+] <tt>:ns => 'uri'|:prefix</tt> Element namespace

 === Example:
    class Cat
      include Peanuts
      ...
      root :kitteh, :ns => 'urn:lol'
      ...
    end