Hello, rmn!
You have to read what it says . . .
Did I do this right?...and any tips on graphing limits?
$\displaystyle f(x)\;=\;\begin{Bmatrix}x & 1 \leq x < 0,\;0 < x \leq 1 \\
1 & x = 0 \\
0 & x < 1,\;x > 1 \end{Bmatrix}$
When $\displaystyle x$ is on the invervals $\displaystyle [1,\,0)$ and $\displaystyle (0,\,1]$
. . we have the line $\displaystyle y \,=\,x$ Code:

 *
 * :
 * :
1  * :
  +    o    +   
: *  1
: * 
: * 
* 
When $\displaystyle x = 0,\:f(0) = 1$ Code:

1* *
 * :
 * :
1  * :
  +    o    +   
: *  1
: * 
: * 
* 
When $\displaystyle x$ is on the intervals $\displaystyle (\infty,\,1)$ and $\displaystyle (1,\,\infty),\;f(x) = 0.$ Code:

* *
 * :
 * :
1  * :
* * * * o    o    o * * * *
: *  1
: * 
: * 
* 