Remember to escape special characters if you do not want them to be
                interpreted as regular expression syntax. For example, `.` appears
                frequently in URLs and should be escaped if you want to match a literal
                `.` rather than any character.
                restrict_to_same_domain takes precedence over filter_urls when
                restrict_to_same_domain is True and the sitemap is not a local file.
            parsing_function: Function to parse bs4.Soup output
            blocksize: number of sitemap locations per block
            blocknum: the number of the block that should be loaded - zero indexed.
                Default: 0
            meta_function: Function to parse bs4.Soup output for metadata
                remember when setting this method to also copy metadata["loc"]
                to metadata["source"] if you are using this field
            is_local: whether the sitemap is a local file. Default: False
            continue_on_failure: whether to continue loading the sitemap if an error
                occurs loading a url, emitting a warning instead of raising an
                exception. Setting this to True makes the loader more robust, but also
                may result in missing data. Default: False
            restrict_to_same_domain: whether to restrict loading to URLs to the same
                domain as the sitemap. Attention: This is only applied if the sitemap
                is not a local file!
        """
        if blocksize is not None and blocksize < 1:
            raise ValueError("Sitemap blocksize should be at least 1")
        if blocknum < 0:
            raise ValueError("Sitemap blocknum can not be lower then 0")
        try:
            import lxml  # noqa:F401
        except ImportError:
            raise ImportError(
                "lxml package not found, please install it with `pip install lxml`"
            )