r"""The tiotal flux for the reaction
        A=[0,...,a] => B=[b,...,M].

        Parameters
        ----------
        a : int
            State index
        b : int
            State index

        Returns
        -------
        F : float
            The total flux between reactant and product

def totalflux(self, a, b):
        r"""The tiotal flux for the reaction
        A=[0,...,a] => B=[b,...,M].

        Parameters
        ----------
        a : int
            State index
        b : int
            State index

        Returns
        -------
        F : float
            The total flux between reactant and product

        """
        flux = self.flux(a, b)
        A = list(range(a + 1))
        notA = list(range(a + 1, flux.shape[0]))
        F = flux[A, :][:, notA].sum()
        return F