docs: def __get_chunk(self, start=0, end=None):
          '''
          Gets chunk from the sar combo file, from start to end
              :param start: where to start a pulled chunk
              :type start: int.
              :param end: where to end a pulled chunk
              :type end: int.
              :return: str.
          '''
          piece = False
  
          if (self.__filename and os.access(self.__filename, os.R_OK)):
  
              fhandle = None
  
              try:
                  fhandle = os.open(self.__filename, os.O_RDONLY)
              except OSError:
                  print(("Couldn't open file %s" % (self.__filename)))
                  fhandle = None
  
              if (fhandle):
  
                  try:
                      sarmap = mmap.mmap(fhandle, length=0, prot=mmap.PROT_READ)
                  except (TypeError, IndexError):
                      os.close(fhandle)
                      traceback.print_exc()
                      #sys.exit(-1)
                      return False
  
                  if (not end):
                      end = sarmap.size()
  
                  try:
                      sarmap.seek(start)
                      piece = sarmap.read(end - start)
                  except:
                      traceback.print_exc()
  
              os.close(fhandle)
  
          return(piece)