Let $\alpha$ be a non-zero real number. Suppose $f:\mathbf{R}\to\mathbf{R}$ is a differentiable function such that $f(0)=2$ and $\displaystyle \lim_{x\to -\infty} f(x)=1$. If $f'(x)=\alpha f(x)+3$, for all $x\in\mathbf{R}$, then $f(-\log_{e}2)$ is equal to: