'Save a chart to a pickle file'

def save_chart(self, *args):

    filename = asksaveasfilename(filetypes=self.CHART_FILE_TYPES, defaultextension='.pickle')
    if (not filename):
        return
    try:
        with open(filename, 'wb') as outfile:
            pickle.dump(self._chart, outfile)
    except Exception as e:
        raise
        showerror('Error    Saving    Chart', ('Unable    to    open    file:    %r' % filename))
