    # File lib/graphviz/graphml.rb, line 38
        def initialize( file_or_str )
          data = ((File.file?( file_or_str )) ? File::new(file_or_str) : file_or_str)
          @xmlDoc = REXML::Document::new( data )
          @attributs = {
            :nodes => {},
            :edges => {},
            :graphs => {}
          }
          @graph = nil
          @current_attr = nil
          @current_node = nil
          @current_edge = nil
          @current_graph = nil

          parse( @xmlDoc.root )
        end