require 'rexml/node'
 require 'rexml/element'
 require 'rexml/document'
 require 'rexml/encoding'
 include REXML

 #Open an existing XML file.
 file = File.new("tree.xml","r")
 doc = REXML::Document.new(file, :ignore_whitespace_nodes => :all)
 tree = doc.root
 
 #print out the attribute 'name' for each leaf node
 puts "Showing all leafs"
 XPath.each(doc.root, '//leaf') { |element| #'trunk/bigbranch/smallbranch/leaf'
   puts element#.text
 }

 #find some information about node
 puts
 puts "Lets find the node that contains the text leaf8!"
 node = tree.find_first_recursive() { |node|
   node.text == 'leaf8'
 }
 if(node != nil)
   puts "index in parent: " + node.index_in_parent().to_s
   puts "parent: "+ node.parent.attributes['name']
   puts "am I a parent?: " + node.parent?.to_s
   if(node.parent?)
     puts "I have " + node.size.to_s + " child(ren) :"
     node.each {|childnode|
       puts childnode.to_s + ", which is a "+ childnode.class.to_s
       }
   end

   puts "prev sibling node: " + node.previous_sibling_node().text
   puts "next sibling node: " + node.next_sibling_node().text
 else
   puts "could not find leaf8"
 end

 #show all the green leafs
 puts
 puts "All the green leafs are "
 tree.each_recursive() { |node|
 if(node.attributes['color'] == 'green')
   puts node.text
 end
 }