Sketch the following function and use it to determine the values of $a$ (list in ascending order below) for which $\displaystyle \lim_{x \to a} f(x)$ does not exist:

$$f(x) = \begin{cases} 2 - x & \textrm{if } x < -1 \\ x & \textrm{if } -1 \leq x < 1 \\ (x - 1)^2 & \textrm{if } x \geq 1 \\ \end{cases}$$

$a =$
$a =$