code: def get_data(self, df):
          
          chart_data = []
          if len(self.groupby) > 0:
              groups = df.groupby(self.groupby)
          else:
              groups = [((), df)]
          for keys, data in groups:
              chart_data.extend([{
                  'key': self.labelify(keys, column),
                  'values': data[column].tolist()}
                  for column in self.columns])
          return chart_data
docs: Returns the chart data