'Construct a new PieChartEncoder.
Args:
is3d: If True, draw a 3d pie chart. Default is False. If the pie chart
includes multiple pies, is3d must be set to False.
angle: Angle of rotation of the pie chart, in radians.'

def __init__(self, chart, is3d=False, angle=None):

    super(PieChartEncoder, self).__init__(chart)
    self.is3d = is3d
    self.angle = None
