def load_stats(self, fdump):
        """
        Load the data from a dump file.
        The argument `fdump` can be either a filename or an open file object
        that requires read access.
        """
        if isinstance(fdump, type('')):
            fdump = open(fdump, 'rb')
        self.index = pickle.load(fdump)
        self.snapshots = pickle.load(fdump)
        self.sorted = []