docs: def open_file(self, fname, length=None, offset=None, swap=None, block=None, peek=None):
          '''
          Opens the specified file with all pertinent configuration settings.
          '''
          if length is None:
              length = self.length
          if offset is None:
              offset = self.offset
          if swap is None:
              swap = self.swap_size
  
          return binwalk.core.common.BlockFile(fname,
                                               subclass=self.subclass,
                                               length=length,
                                               offset=offset,
                                               swap=swap,
                                               block=block,
                                               peek=peek)