docs: def readBinary (self, filename=None):
      """Reads a binary command sequence from the given filename (defaults to
      self.pathname).
      """
      if filename is None:
        filename = self.pathname
  
      stream       = open(filename, 'rb')
      magic        = struct.unpack('>H', stream.read(2))[0]
      self.crc32   = struct.unpack('>I', stream.read(4))[0]
      self.seqid   = struct.unpack('>H', stream.read(2))[0]
      self.version = struct.unpack('>H', stream.read(2))[0]
      ncmds        = struct.unpack('>H', stream.read(2))[0]
      reserved     = stream.read(20)
  
      for n in range(ncmds):
        bytes = stream.read(110)
        self.lines.append( SeqCmd.decode(bytes, self.cmddict) )