def index_of( item )
      max = self.get_length
      #puts "length #{max} #{max.class}"
      counter = 0
      while( counter < max )
        if( get(counter) == item)
          return counter
        end
        counter = counter + 1
      end
      return nil
    end
def index_of( item )
      max = self.get_length
      #puts "length #{max} #{max.class}"
      counter = 0
      while( counter < max )
        if( get(counter) == item)
          return counter
        end
        counter = counter + 1
      end
      return nil
    end
index of item
 return  nil if no such item