(self, extras)
Use this method to add extra d3 properties to your chart.
        For example, you want to change the text color of the graph::

            chart = pieChart(name='pieChart', color_category='category20c', height=400, width=400)

            xdata = ["Orange", "Banana", "Pear", "Kiwi", "Apple", "Strawberry", "Pineapple"]
            ydata = [3, 4, 0, 1, 5, 7, 3]

            extra_serie = {"tooltip": {"y_start": "", "y_end": " cal"}}
            chart.add_serie(y=ydata, x=xdata, extra=extra_serie)

        The above code will create graph with a black text, the following will change it::

            text_white="d3.selectAll('#pieChart text').style('fill', 'white');"
            chart.add_chart_extras(text_white)

        The above extras will be appended to the java script generated.

        Alternatively, you can use the following initialization::

            chart = pieChart(name='pieChart',
                             color_category='category20c',
                             height=400, width=400,
                             extras=text_white)
Use this method to add extra d3 properties to your chart.
        For example, you want to change the text color of the graph::
Use this method to add extra d3 properties to your chart . For example you want to change the text color of the graph ::
def add_chart_extras(self, extras):
        """
        Use this method to add extra d3 properties to your chart.
        For example, you want to change the text color of the graph::

            chart = pieChart(name='pieChart', color_category='category20c', height=400, width=400)

            xdata = ["Orange", "Banana", "Pear", "Kiwi", "Apple", "Strawberry", "Pineapple"]
            ydata = [3, 4, 0, 1, 5, 7, 3]

            extra_serie = {"tooltip": {"y_start": "", "y_end": " cal"}}
            chart.add_serie(y=ydata, x=xdata, extra=extra_serie)

        The above code will create graph with a black text, the following will change it::

            text_white="d3.selectAll('#pieChart text').style('fill', 'white');"
            chart.add_chart_extras(text_white)

        The above extras will be appended to the java script generated.

        Alternatively, you can use the following initialization::

            chart = pieChart(name='pieChart',
                             color_category='category20c',
                             height=400, width=400,
                             extras=text_white)
        """
        self.extras = extras
def add_chart_extras ( self , extras ) : self . extras = extras