def vline_score(self, x, ymin, ymax):
        """Returns the number of unbroken paths of qubits

        >>> [(x,y,1,k) for y in range(ymin,ymax+1)]

        for :math:`k = 0,1,\cdots,L-1`.  This is precomputed for speed.
        """
        return self._vline_score[x, ymin, ymax]
Returns the number of unbroken paths of qubits

        >>> [(x,y,1,k) for y in range(ymin,ymax+1)]

        for :math:`k = 0,1,\cdots,L-1`.  This is precomputed for speed.