(mathOps: MathOps[MathOps[Left]]).*(right)(methodCase)
(mathOps: MathOps[MathOps[Left]]).+(right)(methodCase)
(mathOps: any2stringadd[MathOps[Left]]).+(other)
(mathOps: MathOps[MathOps[Left]]).-(right)(methodCase)
(mathOps: MathOps[MathOps[Left]])./(right)(methodCase)
+, -, *, / are provide by MathMethods and implement in specific
DifferentiableType
such as DifferentiableINDArray