docs: def read (self, filename=None):
      """Reads a 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]
      stream.close()
  
      if magic == Seq.Magic:
        self.readBinary(filename)
      else:
        self.readText(filename)