def METHOD_NAME(self, lattice):
    """
    Args:
        lattice: Lattice parameters in the form of
            [[a_x, a_y, a_z],
             [b_x, b_y, b_z],
             [c_x, c_y, c_z]]
    Returns:
        Metric tensor:
            [[a.a, a.b, a.c],
             [b.a, b.b, b.c],
             [c.a, c.b, c.c]]
    """
    return np.dot(lattice, np.transpose(lattice))