Answer
$y = -4~csc~\frac{1}{2}x$
We can see the graph below.
Work Step by Step
$y = -4~csc~\frac{1}{2}x$
When $x = -2\pi$, then $y = -4~csc~(-\pi)~~$ (which is undefined)
When $x = -\pi$, then $y = -4~csc~(-\frac{\pi}{2}) = 4$
When $x = 0$, then $y = -4~csc~0~~$ (which is undefined)
When $x = \pi$, then $y = -4~csc~(\frac{\pi}{2}) = -4$
When $x = 2\pi$, then $y = -4~csc~\pi~~$ (which is undefined)
We can see the graph below.