def Param(self, param_name, chart=None):
    if chart is None:
      chart = self.chart
    params = chart.display._Params(chart)
    return params[param_name]
Helper to look up a Google Chart API parameter for the given chart.
dataset/ETHPy150Open baz/app-sales-machine/lib/graphy/graphy_test.py/GraphyTest.Param