def _process_environment_cvterm(self):
        """
        This is the mapping between the internal environment id
        and the external ones; here we map the internal environment id to
        the external one in the hashmap.
        :return:

        """

        line_counter = 0
        raw = '/'.join((self.rawdir, 'environment_cvterm'))
        LOG.info("processing environment to cvterm mappings")

        with open(raw, 'r') as f:
            f.readline()  # read the header row; skip
            filereader = csv.reader(f, delimiter='\t', quotechar='\"')
            for line in filereader:
                line_counter += 1

                (environment_cvterm_id, environment_id, cvterm_id) = line
                # 1	1	60468

                environment_key = environment_id

                cvterm_key = cvterm_id
                cvterm_id = self.idhash['cvterm'][cvterm_key]

                # look up the dbxref_id for the cvterm
                # hopefully it's one-to-one
                self.idhash['environment'][environment_key] = cvterm_id

        return
This is the mapping between the internal environment id
        and the external ones; here we map the internal environment id to
        the external one in the hashmap.
        :return: