This is probably a silly question but let me ask.
As it is well known for a general function $f:\mathbb R^2\to \mathbb R$ which posesses partial derivatives of second order it is not necessarily true that
$\frac{\partial}{\partial x}(\frac{\partial f}{\partial y})=\frac{\partial}{\partial y}(\frac{\partial f}{\partial x}) $ and one concrete example is $f(x,y)=\frac{xy^3}{x^2+y^2},$ for $(x,y)\neq (0,0)$ nad $0$ at the origin. My question is about formal complex partial derivatives
$\frac{\partial}{\partial z}=\frac{1}{2}\left(\frac{\partial}{\partial x}-i\frac{\partial}{\partial y}\right)$ $\frac{\partial}{\partial \bar z}=\frac{1}{2}\left(\frac{\partial}{\partial x}+i\frac{\partial}{\partial y}\right)$ in the complex plane $\mathbb C\cong \mathbb R^2 (x+iy\cong z)$.
Is it always true that
$\frac{\partial}{\partial z}(\frac{\partial f}{\partial \bar z})=\frac{\partial}{\partial \bar z}(\frac{\partial f}{\partial z}), $ when both sides make sense or there exists an example of the above type (of course it can not be too regular)?