code: def filter_time_frame(start, delta):
      
      start_value = start
      delta_value = delta
      end_value = None
  
      if start_value is not '':
          start_value = _date_str_to_datetime(start_value)
  
      if delta_value is not '':
          delta_value = _delta_str_to_timedelta(delta_value)
  
      if start_value is not '' and delta_value is not '':
          end_value = start_value + delta_value
  
      def filter_func(log_line):
          if start_value is '':
              return True
          elif start_value > log_line.accept_date:
              return False
  
          if end_value is None:
              return True
          elif end_value < log_line.accept_date:
              return False
  
          return True
  
      return filter_func
docs: Filter :class:`.Line` objects by their connection time.
  
      :param start: a time expression (see -s argument on --help for its format)
        to filter log lines that are before this time.
      :type start: string
      :param delta: a relative time expression (see -s argument on --help for
        its format) to limit the amount of time log lines will be considered.
      :type delta: string
      :returns: a function that filters by the time a request is made.
      :rtype: function