How to use the tinytag.tinytag.Flac function in tinytag

def _determine_duration(self, fh, skip_tags=False):
        # for spec, see https://xiph.org/flac/ogg_mapping.html
        header_data = fh.read(4)
        while len(header_data):
            meta_header = struct.unpack('B3B', header_data)
            block_type = meta_header[0] & 0x7f
            is_last_block = meta_header[0] & 0x80
            size = _bytes_to_int(meta_header[1:4])
            # http://xiph.org/flac/format.html#metadata_block_streaminfo
            if block_type == Flac.METADATA_STREAMINFO:
                stream_info_header = fh.read(size)
                if len(stream_info_header) < 34:  # invalid streaminfo
                    return
                header = struct.unpack('HH3s3s8B16s', stream_info_header)
                # From the ciph documentation:
                # py | 
                # ----------------------------------------------
                # H  | <16>  The minimum block size (in samples)
                # H  | <16>  The maximum block size (in samples)
                # 3s | <24>  The minimum frame size (in bytes)
                # 3s | <24>  The maximum frame size (in bytes)
                # 8B | <20>  Sample rate in Hz.
                #    | <3>   (number of channels)-1.
                #    | <5>   (bits per sample)-1.
                #    | <36>  Total samples in stream.
                # 16s| <128> MD5 signature

def get(cls, filename, tags=True, duration=True):
        parser_class = None
        size = os.path.getsize(filename)
        if not size > 0:
            return TinyTag(None, 0)
        if cls == TinyTag:
            """choose which tag reader should be used by file extension"""
            mapping = {
                ('.mp3',): ID3,
                ('.oga', '.ogg', '.opus'): Ogg,
                ('.wav'): Wave,
                ('.flac'): Flac,
            }
            for fileextension, tagclass in mapping.items():
                if filename.lower().endswith(fileextension):
                    parser_class = tagclass
        else:
            # use class on which the method was invoked as parser
            parser_class = cls
        if parser_class is None:
            raise LookupError('No tag reader found to support filetype! ')
        with open(filename, 'rb') as af:
            tag = parser_class(af, size)
            tag.load(tags=tags, duration=duration)
            return tag

# min_frm = _bytes_to_int(struct.unpack('3B', min_frm))
                # max_frm = _bytes_to_int(struct.unpack('3B', max_frm))
                #                 channels--.  bits      total samples
                # |----- samplerate -----| |-||----| |---------~   ~----|
                # 0000 0000 0000 0000 0000 0000 0000 0000 0000      0000
                # #---4---# #---5---# #---6---# #---7---# #--8-~   ~-12-#
                self.samplerate = _bytes_to_int(header[4:7]) >> 4
                self.channels = ((header[6] >> 1) & 0x07) + 1
                # bit_depth = ((header[6] & 1) << 4) + ((header[7] & 0xF0) >> 4)
                # bit_depth = (bit_depth + 1)
                total_sample_bytes = [(header[7] & 0x0F)] + list(header[8:12])
                total_samples = _bytes_to_int(total_sample_bytes)
                self.duration = float(total_samples) / self.samplerate
                if self.duration > 0:
                    self.bitrate = self.filesize / self.duration * 8 / 1024
            elif block_type == Flac.METADATA_VORBIS_COMMENT and not skip_tags:
                oggtag = Ogg(fh, 0)
                oggtag._parse_vorbis_comment(fh)
                self.update(oggtag)
            elif block_type >= 127:
                return  # invalid block type
            else:
                fh.seek(size, 1)  # seek over this block

            if is_last_block:
                return
            header_data = fh.read(4)

def _get_parser_for_filename(cls, filename, exception=False):
        mapping = {
            ('.mp3',): ID3,
            ('.oga', '.ogg', '.opus'): Ogg,
            ('.wav',): Wave,
            ('.flac',): Flac,
            ('.wma',): Wma,
            ('.m4b', '.m4a', '.mp4'): MP4,
        }
        for fileextension, tagclass in mapping.items():
            if filename.lower().endswith(fileextension):
                return tagclass
        if exception:
            raise TinyTagException('No tag reader found to support filetype! ')