Find $\lim \_{ n\rightarrow \infty }{ { \left( { 3 }^{ n }+1 \right) }^{ \frac { 1 }{ n } } } $ using the **squeeze** theorem

I have come across ways to do this but none mention the squeeze (or sandwich) theorem. I know I need to find $2$ functions which squeeze the given function but can only think of using $(3^n)^{1/n}$ i.e. $3$ as the $\le $ function