docs: def __parseFormat(self, fmt, content, fps = 25):
          '''Actual parser. Please note that time_to is not required to process as not all subtitles
          provide it.'''
  
          headerFound = False
          subSection = ''
          for lineNo, line in enumerate(content):
              line = self._initialLinePrepare(line, lineNo)
              if not fmt.WITH_HEADER and not self._formatFound and lineNo > self._maxFmtSearch:
                  return
  
              subSection = ''.join([subSection, line])
              if fmt.WITH_HEADER and not headerFound:
                  if lineNo > self._maxHeaderLen:
                      return
                  headerFound = fmt.addHeaderInfo(subSection, self._subtitles.header())
                  if headerFound:
                      self._formatFound = True
                      subSection = ''
              elif fmt.subtitleEnds(line) or (lineNo + 1) == len(content):
                  subtitle = fmt.createSubtitle(fps, subSection)
                  if subtitle is None:
                      if subSection in ('\n', '\r\n', '\r'):
                          subSection = ''
                          continue
                      elif self._subtitles.size() > 0:
                          raise SubParsingError(_("Parsing error"), lineNo)
                      else:
                          return
  
                  # store parsing result if new end marker occurred, then clear results
                  if subtitle.start and subtitle.text:
                      self._formatFound = True
                      try:
                          self._subtitles.append(subtitle)
                      except SubException as msg:
                          raise SubParsingError(msg, lineNo)
                  elif subtitle.start and not subtitle.text:
                      pass
                  else:
                      return
                  subSection = ''