$$l+\frac{1}{x\rightarrow\infty}\frac{2^{y}-2^{-y}}{2^{y}+2^{-y}}$$
$\frac{3\left(4^{y}-1\right)}{4^{y}+1}$
$\frac{12\ln(2)\times 4^{y}}{2\times 4^{y}+16^{y}+1}$
