Answer
$y=-\cot{x}$
Work Step by Step
The given function has the vertical asymptotes $x=0$ and $x=\pi$.
This means that the function involved must be the cotangent function.
Note however, that the basic cotangent function $y=\cot{x}$ is decreasing in its entire domain.
The given graph is increasing in its entire domain.
This means that it must involve a reflection about the x-axis of $y=\cot{x}$.
Therefore, the equation of the function whose graph is given must be $\color{blue}{y=-\cot{x}}$.
Graphing this function matches the given graph. (refer to the graph below.)
