How to use the pystac.utils.make_absolute_href function in pystac

cat_dict = STAC_IO.read_json(href)
            cat = STACObject.from_file(href)
            for link in cat.get_links():
                if not link.rel == 'self':
                    self.assertEqual(link.link_type, link_type)

            rels = set([l['rel'] for l in cat_dict['links']])
            self.assertEqual('self' in rels, should_include_self)

            for child_link in cat.get_child_links():
                child_href = make_absolute_href(child_link.target, href)
                validate_catalog_link_type(child_href, link_type,
                                           catalog_type == CatalogType.ABSOLUTE_PUBLISHED)

            for item_link in cat.get_item_links():
                item_href = make_absolute_href(item_link.target, href)
                validate_item_link_type(item_href, link_type,
                                        catalog_type == CatalogType.ABSOLUTE_PUBLISHED)

def validate_catalog_link_type(href, link_type, should_include_self):
            cat_dict = STAC_IO.read_json(href)
            cat = STACObject.from_file(href)
            for link in cat.get_links():
                if not link.rel == 'self':
                    self.assertEqual(link.link_type, link_type)

            rels = set([l['rel'] for l in cat_dict['links']])
            self.assertEqual('self' in rels, should_include_self)

            for child_link in cat.get_child_links():
                child_href = make_absolute_href(child_link.target, href)
                validate_catalog_link_type(child_href, link_type,
                                           catalog_type == CatalogType.ABSOLUTE_PUBLISHED)

            for item_link in cat.get_item_links():
                item_href = make_absolute_href(item_link.target, href)
                validate_item_link_type(item_href, link_type,
                                        catalog_type == CatalogType.ABSOLUTE_PUBLISHED)

def get_absolute_href(self):
        """Gets the aboslute href for this link, if possible.

        Returns:
            str: Returns this link's HREF. It attempts to derive an absolute HREF
            from this link; however, if the link is relative, has no owner,
            and has an unresolved target, this will return a relative HREF.
        """
        if self.is_resolved():
            href = self.target.get_self_href()
        else:
            href = self.target

        if self.owner is not None:
            href = make_absolute_href(href, self.owner.get_self_href())

        return href

def normalize_hrefs(self, root_href):
        if not is_absolute_href(root_href):
            root_href = make_absolute_href(root_href, os.getcwd(), start_is_dir=True)

        old_self_href = self.get_self_href()
        new_self_href = os.path.join(root_href, '{}.json'.format(self.id))
        self.set_self_href(new_self_href)

        # Make sure relative asset links remain valid.
        # This will only work if there is a self href set.
        for asset in self.assets.values():
            asset_href = asset.href
            if not is_absolute_href(asset_href):
                if old_self_href is not None:
                    abs_href = make_absolute_href(asset_href, old_self_href)
                    new_relative_href = make_relative_href(abs_href, new_self_href)
                    asset.href = new_relative_href

def normalize_hrefs(self, root_href):
        if not is_absolute_href(root_href):
            root_href = make_absolute_href(root_href, os.getcwd(), start_is_dir=True)

        old_self_href = self.get_self_href()
        new_self_href = os.path.join(root_href, '{}.json'.format(self.id))
        self.set_self_href(new_self_href)

        # Make sure relative asset links remain valid.
        # This will only work if there is a self href set.
        for asset in self.assets.values():
            asset_href = asset.href
            if not is_absolute_href(asset_href):
                if old_self_href is not None:
                    abs_href = make_absolute_href(asset_href, old_self_href)
                    new_relative_href = make_relative_href(abs_href, new_self_href)
                    asset.href = new_relative_href

def from_file(cls, href):
        """Reads a STACObject implementation from a file.

        Args:
            href (str): The HREF to read the object from.

        Returns:
            The specific STACObject implementation class that is represented
            by the JSON read from the file located at HREF.
        """
        if not is_absolute_href(href):
            href = make_absolute_href(href)
        d = STAC_IO.read_json(href)

        if cls == STACObject:
            o = STAC_IO.stac_object_from_dict(d, href=href)
        else:
            o = cls.from_dict(d, href=href)

        # Set the self HREF, if it's not already set to something else.
        if o.get_self_href() is None:
            o.set_self_href(href)

        # If this is a root catalog, set the root to the catalog instance.
        root_link = o.get_root_link()
        if root_link is not None:
            if not root_link.is_resolved():
                if root_link.get_absolute_href() == href:

def normalize_hrefs(self, root_href):
        # Normalizing requires an absolute path
        if not is_absolute_href(root_href):
            root_href = make_absolute_href(root_href, os.getcwd(), start_is_dir=True)

        # Fully resolve the STAC to avoid linking issues.
        # This particularly can happen with unresolved links that have
        # relative paths.
        self.fully_resolve()

        for child in self.get_children():
            child_root = os.path.join(root_href, '{}/'.format(child.id))
            child.normalize_hrefs(child_root)

        for item in self.get_items():
            item_root = os.path.join(root_href, '{}'.format(item.id))
            item.normalize_hrefs(item_root)

        self.set_self_href(os.path.join(root_href, self.DEFAULT_FILE_NAME))

if collection_cache is not None:
            collection = collection_cache.get_by_id(collection_id)

    # Next, try the collection link.
    if collection is None:
        links = item_dict['links']

        # Account for 0.5 links, which were dicts
        if isinstance(links, dict):
            links = list(links.values())

        collection_link = next((link for link in links if link['rel'] == 'collection'), None)
        if collection_link is not None:
            collection_href = collection_link['href']
            if json_href is not None:
                collection_href = make_absolute_href(collection_href, json_href)
            if collection_cache is not None:
                collection = collection_cache.get_by_href(collection_href)

            if collection is None:
                collection = STAC_IO.read_json(collection_href)

    if collection is not None:
        collection_id = None
        collection_props = None
        if isinstance(collection, Collection):
            collection_id = collection.id
            collection_props = collection.properties
        else:
            collection_id = collection['id']
            if 'properties' in collection:
                collection_props = collection['properties']