def get_params(self, *keys):
        """Returns the specified parameters for the current preprocessor.

        Parameters:
        -----------
        keys : variable sized list, containing the names of the requested parameters

        Returns:
        --------
        values : list or dictionary, if any `keys` are specified
        those named parameters' values are returned, otherwise
        all parameters are returned as a dictionary
        
        """

        if len(keys) == 0:
            return vars(self)
        else:
            return [vars(self)[k] for k in keys]