'**Arguments:**
orientation     Set the orientation of the gradient. Options are: \'left\', \'right\'
\'top\', and \'bottom\'.
allowAdd        Specifies whether ticks can be added to the item by the user.
tickPen         Default is white. Specifies the color of the outline of the ticks.
Can be any of the valid arguments for :func:`mkPen <pyqtgraph.mkPen>`'

def __init__(self, orientation='bottom', allowAdd=True, **kargs):

    GraphicsWidget.__init__(self)
    self.orientation = orientation
    self.length = 100
    self.tickSize = 15
    self.ticks = {}
    self.maxDim = 20
    self.allowAdd = allowAdd
    if ('tickPen' in kargs):
        self.tickPen = fn.mkPen(kargs['tickPen'])
    else:
        self.tickPen = fn.mkPen('w')
    self.orientations = {'left': (90, 1, 1), 'right': (90, 1, 1), 'top': (0, 1, (-1)), 'bottom': (0, 1, 1)}
    self.setOrientation(orientation)
