How to use the datalad.cfg.obtain function in datalad

def get_url_cache_filename(url, name=None):
    """Return a filename where to cache online doc from a url"""
    if not name:
        name = "misc"
    cache_dir = opj(cfg.obtain('datalad.locations.cache'), name)
    doc_fname = opj(
        cache_dir,
        '{}-{}.p{}'.format(
            urlsplit(url).netloc,
            md5(url.encode('utf-8')).hexdigest(),
            pickle.HIGHEST_PROTOCOL)
    )
    return doc_fname

if not exists(index_dir):
            os.makedirs(index_dir)

        # this is a pretty cheap call that just pull this info from a file
        dsinfo = self.ds.metadata(
            get_aggregates=True,
            return_type='list',
            result_renderer='disabled')

        self._mk_schema(dsinfo)

        idx_obj = widx.create_in(index_dir, self.schema)
        idx = idx_obj.writer(
            # cache size per process
            limitmb=cfg.obtain('datalad.search.indexercachesize'),
            # disable parallel indexing for now till #1927 is resolved
            ## number of processes for indexing
            #procs=multiprocessing.cpu_count(),
            ## write separate index segments in each process for speed
            ## asks for writer.commit(optimize=True)
            #multisegment=True,
        )

        # load metadata of the base dataset and what it knows about all its subdatasets
        # (recursively)
        old_idx_size = 0
        old_ds_rpath = ''
        idx_size = 0
        log_progress(
            lgr.info,
            'autofieldidxbuild',

before), the addition (or just an update) of a (sub-)dataset would otherwise
    surprisingly cause you do execute code different from what you defined
    within ~/.gitconfig or your local repository's .git/config.
    So, local definitions take precedence over remote ones and more specific
    ones over more general ones.

    Returns
    -------
    tuple
      path, name, format string, help message
    """

    ds = ds if isinstance(ds, Dataset) else Dataset(ds) if ds else None

    # 1. check system and user account for procedure
    for loc in (cfg.obtain('datalad.locations.user-procedures'),
                cfg.obtain('datalad.locations.system-procedures')):
        for dir in assure_list(loc):
            for m, n in _get_file_match(dir, name):
                yield (m, n,) + _get_proc_config(n)
    # 2. check dataset for procedure
    if ds is not None and ds.is_installed():
        # could be more than one
        dirs = assure_list(
                ds.config.obtain('datalad.locations.dataset-procedures'))
        for dir in dirs:
            # TODO `get` dirs if necessary
            for m, n in _get_file_match(op.join(ds.path, dir), name):
                yield (m, n,) + _get_proc_config(n, ds=ds)
        # 2.1. check subdatasets recursively
        for subds in ds.subdatasets(return_type='generator',
                                    result_xfm='datasets'):

def _get_result_filter(cls, args):
        from datalad import cfg
        result_filter = None
        if args.common_report_status or 'datalad.runtime.report-status' in cfg:
            report_status = args.common_report_status or \
                            cfg.obtain('datalad.runtime.report-status')
            if report_status == "all":
                pass  # no filter
            elif report_status == 'success':
                result_filter = EnsureKeyChoice('status', ('ok', 'notneeded'))
            elif report_status == 'failure':
                result_filter = EnsureKeyChoice('status',
                                                ('impossible', 'error'))
            else:
                result_filter = EnsureKeyChoice('status', (report_status,))
        if args.common_report_type:
            tfilt = EnsureKeyChoice('type', tuple(args.common_report_type))
            result_filter = result_filter & tfilt if result_filter else tfilt
        return result_filter

git_opts=initopts,
                fake_dates=fake_dates
            )
            # set the annex backend in .gitattributes as a staged change
            tbrepo.set_default_backend(
                cfg.obtain('datalad.repo.backend'),
                persistent=True, commit=False)
            add_to_git[tbds.repo.pathobj / '.gitattributes'] = {
                'type': 'file',
                'state': 'added'}
            # make sure that v6 annex repos never commit content under .datalad
            attrs_cfg = (
                ('config', 'annex.largefiles', 'nothing'),
                ('metadata/aggregate*', 'annex.largefiles', 'nothing'),
                ('metadata/objects/**', 'annex.largefiles',
                 '({})'.format(cfg.obtain(
                     'datalad.metadata.create-aggregate-annex-limit'))))
            attrs = tbds.repo.get_gitattributes(
                [op.join('.datalad', i[0]) for i in attrs_cfg])
            set_attrs = []
            for p, k, v in attrs_cfg:
                if not attrs.get(
                        op.join('.datalad', p), {}).get(k, None) == v:
                    set_attrs.append((p, {k: v}))
            if set_attrs:
                tbds.repo.set_gitattributes(
                    set_attrs,
                    attrfile=op.join('.datalad', '.gitattributes'))

            # prevent git annex from ever annexing .git* stuff (gh-1597)
            attrs = tbds.repo.get_gitattributes('.git')
            if not attrs.get('.git', {}).get(

tbrepo = AnnexRepo(
                tbds.path,
                url=None,
                create=True,
                create_sanity_checks=False,
                # do not set backend here, to avoid a dedicated commit
                backend=None,
                # None causes version to be taken from config
                version=None,
                description=description,
                git_opts=initopts,
                fake_dates=fake_dates
            )
            # set the annex backend in .gitattributes as a staged change
            tbrepo.set_default_backend(
                cfg.obtain('datalad.repo.backend'),
                persistent=True, commit=False)
            add_to_git[tbds.repo.pathobj / '.gitattributes'] = {
                'type': 'file',
                'state': 'added'}
            # make sure that v6 annex repos never commit content under .datalad
            attrs_cfg = (
                ('config', 'annex.largefiles', 'nothing'),
                ('metadata/aggregate*', 'annex.largefiles', 'nothing'),
                ('metadata/objects/**', 'annex.largefiles',
                 '({})'.format(cfg.obtain(
                     'datalad.metadata.create-aggregate-annex-limit'))))
            attrs = tbds.repo.get_gitattributes(
                [op.join('.datalad', i[0]) for i in attrs_cfg])
            set_attrs = []
            for p, k, v in attrs_cfg:
                if not attrs.get(