$S$-unit values of $G_n+G_m$ in function fields

In this paper, we consider a simple linear recurrence sequence $G_n $ defined over a function field in one variable over the field of complex numbers. We prove an upper bound on the indices $n$ and $m$ such that $G_n+G_m$ is an $S$-unit. This is a function field analogue of already known results in number fields.