How to use the siphon.catalog.DatasetCollection function in siphon

"""Same as siphon.catalog.TDSCatalog, but with constructor which takes url and response

        So it can be used by a generic asynchronous web crawler

        Args:
            catalog_url: URL with THREDDS catalog xml file
            content: Content found at catalog_url
        """
        self.catalog_url = catalog_url
        self.base_tds_url = _find_base_tds_url(self.catalog_url)

        # begin parsing the xml doc
        root = ET.fromstring(content)
        self.catalog_name = root.attrib.get('name', 'No name found')

        self.datasets = DatasetCollection()
        self.services = []
        self.catalog_refs = DatasetCollection()
        self.metadata = {}
        self.ds_with_access_elements_to_process = []
        service_skip_count = 0
        service_skip = 0
        current_dataset = None
        previous_dataset = None
        for child in root.iter():
            tag_type = child.tag.split('}')[-1]
            if tag_type == 'dataset':
                current_dataset = child.attrib['name']
                self._process_dataset(child)

                # see if the previously processed dataset has access elements as children
                # if so, these datasets need to be processed specially when making

So it can be used by a generic asynchronous web crawler

        Args:
            catalog_url: URL with THREDDS catalog xml file
            content: Content found at catalog_url
        """
        self.catalog_url = catalog_url
        self.base_tds_url = _find_base_tds_url(self.catalog_url)

        # begin parsing the xml doc
        root = ET.fromstring(content)
        self.catalog_name = root.attrib.get('name', 'No name found')

        self.datasets = DatasetCollection()
        self.services = []
        self.catalog_refs = DatasetCollection()
        self.metadata = {}
        self.ds_with_access_elements_to_process = []
        service_skip_count = 0
        service_skip = 0
        current_dataset = None
        previous_dataset = None
        for child in root.iter():
            tag_type = child.tag.split('}')[-1]
            if tag_type == 'dataset':
                current_dataset = child.attrib['name']
                self._process_dataset(child)

                # see if the previously processed dataset has access elements as children
                # if so, these datasets need to be processed specially when making
                # access_urls
                if previous_dataset and self.datasets[previous_dataset].access_element_info:

# If we were given an HTML link, warn about it and try to fix to xml
        if 'html' in resp.headers['content-type']:
            import warnings
            new_url = self.catalog_url.replace('html', 'xml')
            warnings.warn('URL {} returned HTML. Changing to: {}'.format(self.catalog_url,
                                                                         new_url))
            self.catalog_url = new_url
            resp = self.session.get(self.catalog_url)
            resp.raise_for_status()

        # begin parsing the xml doc
        root = ET.fromstring(resp.content)
        self.catalog_name = root.attrib.get('name', 'No name found')

        self.datasets = DatasetCollection()
        self.services = []
        self.catalog_refs = DatasetCollection()
        self.metadata = {}
        self.ds_with_access_elements_to_process = []
        service_skip_count = 0
        service_skip = 0
        current_dataset = None
        previous_dataset = None
        for child in root.iter():
            tag_type = child.tag.split('}')[-1]
            if tag_type == 'dataset':
                current_dataset = child.attrib['name']
                self._process_dataset(child)

                if previous_dataset:
                    # see if the previously processed dataset has access elements as children

if 'html' in resp.headers['content-type']:
            import warnings
            new_url = self.catalog_url.replace('html', 'xml')
            warnings.warn('URL {} returned HTML. Changing to: {}'.format(self.catalog_url,
                                                                         new_url))
            self.catalog_url = new_url
            resp = self.session.get(self.catalog_url)
            resp.raise_for_status()

        # begin parsing the xml doc
        root = ET.fromstring(resp.content)
        self.catalog_name = root.attrib.get('name', 'No name found')

        self.datasets = DatasetCollection()
        self.services = []
        self.catalog_refs = DatasetCollection()
        self.metadata = {}
        self.ds_with_access_elements_to_process = []
        service_skip_count = 0
        service_skip = 0
        current_dataset = None
        previous_dataset = None
        for child in root.iter():
            tag_type = child.tag.split('}')[-1]
            if tag_type == 'dataset':
                current_dataset = child.attrib['name']
                self._process_dataset(child)

                if previous_dataset:
                    # see if the previously processed dataset has access elements as children
                    # if so, these datasets need to be processed specially when making
                    # access_urls