In the following class,$$WT is a$($n$)\_\_\_\_\_\_\_\_\_\_$ variable.

class VolumeRobot$($object$)$:

WT $=200$

def init$($self$,$ r$,$ h$)$:

self.radius $=$ r

self.height $=$ h

def calcArea$($self$)$:

self.area $=$ math.pi $*$ self.radius $**2$

def calcVolume$($self$)$:

self.volume $=$ self.area $*$ self.height;

heaviness $=10$

self.bulk $=$ heaviness $*$ VolumeRobot.WT $*$ self.volume

def str$($self$)$:

return "Radius: $\%0\mathrm{.}2$f$,$ Area: $\%0\mathrm{.}2$f$,$ Volume: $\%0\mathrm{.}2$f$"\%($self$.$radius, self.area, self.volume$)$