def to_xml(options = {})
      xml = options[:builder] ||= Builder::XmlMarkup.new
      xml.instruct! unless options[:skip_instruct]
      xml.member(:type => type, :ref => ref, :role => role)
    end
def to_xml(options = {})
      xml = options[:builder] ||= Builder::XmlMarkup.new
      xml.instruct! unless options[:skip_instruct]
      xml.member(:type => type, :ref => ref, :role => role)
    end
Create a new Member object. Type can be one of 'node', 'way' or
 'relation'. Ref is the ID of the corresponding Node, Way, or
 Relation. Role is a freeform string and can be empty.
 Return XML for this way. This method uses the Builder library.
 The only parameter ist the builder object.