How to use the pyfaidx.__init__.UnsupportedCompressionFormat function in pyfaidx

def __init__(self, name, fa):
        super(MutableFastaRecord, self).__init__(name, fa)
        if self._fa.faidx._fasta_opener != open:
            raise UnsupportedCompressionFormat(
                "BGZF compressed FASTA is not supported for MutableFastaRecord. "
                "Please decompress your FASTA file.")

self._bgzf = True
        elif filename.lower().endswith('.bz2') or filename.lower().endswith(
                '.zip'):
            raise UnsupportedCompressionFormat(
                "Compressed FASTA is only supported in BGZF format. Use "
                "bgzip to compresss your FASTA.")
        else:
            self._fasta_opener = open
            self._bgzf = False

        try:
            self.file = self._fasta_opener(filename, 'r+b'
                                           if mutable else 'rb')
        except (ValueError, IOError) as e:
            if str(e).find('BGZF') > -1:
                raise UnsupportedCompressionFormat(
                    "Compressed FASTA is only supported in BGZF format. Use "
                    "the samtools bgzip utility (instead of gzip) to "
                    "compress your FASTA.")
            else:
                raise FastaNotFoundError(
                    "Cannot read FASTA file %s" % filename)

        self.indexname = filename + '.fai'
        self.read_long_names = read_long_names
        self.key_function = key_function
        try:
            key_fn_test = self.key_function(
                "TestingReturnType of_key_function")
            if not isinstance(key_fn_test, string_types):
                raise KeyFunctionError(
                    "key_function argument should return a string, not {0}".

# Only try to import Bio if we actually need the bgzf reader.
            try:
                from Bio import bgzf
                from Bio import __version__ as bgzf_version
                from distutils.version import LooseVersion
                if LooseVersion(bgzf_version) < LooseVersion('1.73'):
                    raise ImportError
            except ImportError:
                raise ImportError(
                    "BioPython >= 1.73 must be installed to read block gzip files.")
            else:
                self._fasta_opener = bgzf.open
                self._bgzf = True
        elif filename.lower().endswith('.bz2') or filename.lower().endswith(
                '.zip'):
            raise UnsupportedCompressionFormat(
                "Compressed FASTA is only supported in BGZF format. Use "
                "bgzip to compresss your FASTA.")
        else:
            self._fasta_opener = open
            self._bgzf = False

        try:
            self.file = self._fasta_opener(filename, 'r+b'
                                           if mutable else 'rb')
        except (ValueError, IOError) as e:
            if str(e).find('BGZF') > -1:
                raise UnsupportedCompressionFormat(
                    "Compressed FASTA is only supported in BGZF format. Use "
                    "the samtools bgzip utility (instead of gzip) to "
                    "compress your FASTA.")
            else: