left invariant derivation

Question

I have defined a derivation in the following way: Let K be a vector field, A a K-algebra, a derivation $D$ is suhch that $D\in Hom_K(A,A)$ and $D(fg)=D(f)g+D(g)f$. Let here be $A=K[T]$, the ring of polynomials. I am having trouble finding an example of a left invariant derivation ( a derivation that commutes with the left traslation of functions)