'Set the orientation of the TickSliderItem.
**Arguments:**
orientation     Options are: \'left\', \'right\', \'top\', \'bottom\'
The orientation option specifies which side of the slider the
ticks are on, as well as whether the slider is vertical (\'right\'
and \'left\') or horizontal (\'top\' and \'bottom\').'

def setOrientation(self, orientation):

    self.orientation = orientation
    self.setMaxDim()
    self.resetTransform()
    ort = orientation
    if (ort == 'top'):
        transform = QtGui.QTransform.fromScale(1, (-1))
        transform.translate(0, (- self.height()))
        self.setTransform(transform)
    elif (ort == 'left'):
        transform = QtGui.QTransform()
        transform.rotate(270)
        transform.scale(1, (-1))
        transform.translate((- self.height()), (- self.maxDim))
        self.setTransform(transform)
    elif (ort == 'right'):
        transform = QtGui.QTransform()
        transform.rotate(270)
        transform.translate((- self.height()), 0)
        self.setTransform(transform)
    elif (ort != 'bottom'):
        raise Exception(("%s    is    not    a    valid    orientation.    Options    are    'left',    'right',    'top',    and    'bottom'" % str(ort)))
    self.translate((self.tickSize / 2.0), 0)
