'Set the pen used to draw graph lines.
May be:
* None to disable line drawing
* Record array with fields (red, green, blue, alpha, width)
* Any set of arguments and keyword arguments accepted by
:func:`mkPen <pyqtgraph.mkPen>`.
* \'default\' to use the default foreground color.'

def setPen(self, *args, **kwargs):

    if ((len(args) == 1) and (len(kwargs) == 0)):
        self.pen = args[0]
    else:
        self.pen = fn.mkPen(*args, **kwargs)
    self.picture = None
    self.update()
