# File lib/facet/harray.rb, line 197
  def compact!
    if self.has_value?(nil)
      nha, j = HArray.new, 0
      (0..self.length-1).each do |i|
        if self.fetch(i) != nil
          nha.set(j,self.fetch(i))
          j+=1
        end
      end
      return self.replace(nha)
    else
      return nil
    end
  end