'Add a pie segment to this chart, and return the segment.
size: The size of the segment.
label: The label for the segment.
color: The color of the segment, or None to automatically choose the color.
pie_index: The index of the pie that will receive the new segment.
By default, the chart has one pie (pie #0); use the AddPie method to
add more pies.'

def AddSegment(self, size, label=None, color=None, pie_index=0):

    if isinstance(size, Segment):
        warnings.warn('AddSegment(segment)    is    deprecated.        Use    AddSegment(size,    label,    color)    instead', DeprecationWarning, stacklevel=2)
        segment = size
    else:
        segment = Segment(size, label=label, color=color)
    assert (segment.size >= 0)
    if ((pie_index == 0) and (not self.data)):
        self.data.append([])
    assert ((pie_index >= 0) and (pie_index < len(self.data)))
    self.data[pie_index].append(segment)
    return segment
