# File lib/rbreadline.rb, line 5360
  def replace_history_entry (which, line, data)
    if (which < 0 || which >= @history_length)
      return nil
    end
    temp = Struct.new(:line,:timestamp,:data).new
    old_value = @the_history[which]
    temp.line = line.delete(0.chr)
    temp.data = data
    temp.timestamp = old_value.timestamp.dup
    @the_history[which] = temp
    old_value
  end