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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_sigmoid_parameters(self, filename='shlp_sigmoid_factors.csv'):
 """ Retrieve the sigmoid parameters from csv-files Parameters filename : string name of file where sigmoid factors are stored """


        file = os.path.join(self.datapath, filename)
        sigmoid = pd.read_csv(file, index_col=0)
        sigmoid = sigmoid.query(
            'building_class=={0} and '.format(self.building_class) +
            'shlp_type=="{0}" and '.format(self.shlp_type) +
            'wind_impact=={0}'.format(self.wind_class))

        a = float(sigmoid['parameter_a'])
        b = float(sigmoid['parameter_b'])
        c = float(sigmoid['parameter_c'])
        if self.ww_incl:
            d = float(sigmoid['parameter_d'])
        else:
            d = 0
        return a, b, c, d