def process_data(self, data, **kwargs):
cloud_cover = '<STR_LIT>'<EOL>data = super(NDFD, self).process_data(data, **kwargs)<EOL>data['<STR_LIT>'] = self.kelvin_to_celsius(data['<STR_LIT>'])<EOL>irrads = self.cloud_cover_to_irradiance(data[cloud_cover], **kwargs)<EOL>data = data.join(irrads, how='<STR_LIT>')<EOL>return data[self.output_variables]<EOL>
Defines the steps needed to convert raw forecast data
into processed forecast data.

Parameters
----------
data: DataFrame
    Raw forecast data

Returns
-------
data: DataFrame
    Processed forecast data.