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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 drop_prior_information(self):
 """drop the prior information from the jco and pst attributes """

        if self.jco is None:
            self.logger.statement("can't drop prior info, LinearAnalysis.jco is None")
            return
        nprior_str = str(self.pst.nprior)
        self.log("removing " + nprior_str + " prior info from jco, pst, and " +
                                            "obs cov")
        #pi_names = list(self.pst.prior_information.pilbl.values)
        pi_names = list(self.pst.prior_names)
        missing = [name for name in pi_names if name not in self.jco.obs_names]
        if len(missing) > 0:
            raise Exception("LinearAnalysis.drop_prior_information(): "+
                            " prior info not found: {0}".format(missing))
        if self.jco is not None:
            self.__jco.drop(pi_names, axis=0)
        self.__pst.prior_information = self.pst.null_prior
        self.__pst.control_data.pestmode = "estimation"
        #self.__obscov.drop(pi_names,axis=0)
        self.log("removing " + nprior_str + " prior info from jco, pst, and " +
                                            "obs cov")