code: def is_extent_valid(self, start_time, duration, flag=None):
          
          sr = self.raw_buffer.sample_rate
          s = int((start_time - self.raw_buffer.start_time) * sr)
          e = s + int(duration * sr) + 1
          data = self.raw_buffer[s:e]
          return self.check_valid(data, flag=flag)
docs: Check if the duration contains any non-valid frames
  
          Parameters
          ----------
          start_time: int
              Beginning of the duration to check in gps seconds
          duration: int
              Number of seconds after the start_time to check
          flag: str, optional
              Override the default valid mask with a user defined mask.
  
          Returns
          -------
          status: boolean
              Returns True if all of the status information if valid,
              False if any is not.