'Changes the appearance of the arrow.
All arguments are optional:
**Keyword Arguments:**
angle                   Orientation of the arrow in degrees. Default is
0; arrow pointing to the left.
headLen                 Length of the arrow head, from tip to base.
default=20
headWidth               Width of the arrow head at its base.
tipAngle                Angle of the tip of the arrow in degrees. Smaller
values make a \'sharper\' arrow. If tipAngle is
specified, ot overrides headWidth. default=25
baseAngle               Angle of the base of the arrow head. Default is
0, which means that the base of the arrow head
is perpendicular to the arrow tail.
tailLen                 Length of the arrow tail, measured from the base
of the arrow head to the end of the tail. If
this value is None, no tail will be drawn.
default=None
tailWidth               Width of the tail. default=3
pen                     The pen used to draw the outline of the arrow.
brush                   The brush used to fill the arrow.'

def setStyle(self, **opts):

    self.opts.update(opts)
    opt = dict([(k, self.opts[k]) for k in ['headLen', 'tipAngle', 'baseAngle', 'tailLen', 'tailWidth']])
    self.path = fn.makeArrowPath(**opt)
    self.setPath(self.path)
    self.setPen(fn.mkPen(self.opts['pen']))
    self.setBrush(fn.mkBrush(self.opts['brush']))
    if self.opts['pxMode']:
        self.setFlags((self.flags() | self.ItemIgnoresTransformations))
    else:
        self.setFlags((self.flags() & (~ self.ItemIgnoresTransformations)))
