How to use the signac.core.json.loads function in signac

try:
        job_ids = [jid for jid in os.listdir(root) if m.match(jid)]
    except OSError as error:
        if error.errno == errno.ENOENT:
            return
        else:
            raise
    for i, job_id in enumerate(job_ids):
        if not m.match(job_id):
            continue
        doc = {'signac_id': job_id, KEY_PATH: root}
        if signac_id_alias:
            doc[signac_id_alias] = job_id
        fn_sp = os.path.join(root, job_id, fn_statepoint)
        with open(fn_sp, 'rb') as file:
            sp = json.loads(file.read().decode(encoding))
            if statepoint_dict is not None:
                statepoint_dict[job_id] = sp
            if statepoint_index:
                doc[statepoint_index] = sp
            else:
                doc.update(sp)
        if include_job_document:
            fn_doc = os.path.join(root, job_id, fn_job_document)
            try:
                with open(fn_doc, 'rb') as file:
                    doc.update(json.loads(file.read().decode(encoding)))
            except IOError as error:
                if error.errno != errno.ENOENT:
                    raise
        yield doc
    if job_ids:

def _build_index(self, include_job_document=False):
        """
        Generate a basic state point index.
        """
        wd = self.workspace() if self.Job is Job else None
        for _id in self._find_job_ids():
            doc = dict(_id=_id, statepoint=self._get_statepoint(_id))
            if include_job_document:
                if wd is None:
                    doc.update(self.open_job(id=_id).document)
                else:   # use optimized path
                    try:
                        with open(os.path.join(wd, _id, self.Job.FN_DOCUMENT), 'rb') as file:
                            doc.update(json.loads(file.read().decode()))
                    except IOError as error:
                        if error.errno != errno.ENOENT:
                            raise
            yield doc

def read_statepoints(self, fn=None):
        """Read all statepoints from a file.

        :param fn: The filename of the file containing the statepoints,
            defaults to :const:`~signac.contrib.project.Project.FN_STATEPOINTS`.
        :type fn: str

        See also :meth:`dump_statepoints` and :meth:`write_statepoints`.
        """
        if fn is None:
            fn = self.fn(self.FN_STATEPOINTS)
        # See comment in write statepoints.
        with open(fn, 'r') as file:
            return json.loads(file.read())

def _read_cache(self):
        "Read the persistent state point cache (if available)."
        logger.debug("Reading cache...")
        start = time.time()
        try:
            with gzip.open(self.fn(self.FN_CACHE), 'rb') as cachefile:
                cache = json.loads(cachefile.read().decode())
            self._sp_cache.update(cache)
        except IOError as error:
            if not error.errno == errno.ENOENT:
                raise
            logger.debug("No cache file found.")
        else:
            delta = time.time() - start
            logger.debug("Read cache in {:.3f} seconds.".format(delta))
            return cache