How to use the pymtp.LIBMTP_Track function in PyMTP

("storage_id", ctypes.c_uint32),
                        ("filename", ctypes.c_char_p),
                        ("filesize", ctypes.c_uint64),
			("filetype", ctypes.c_int),
			("next", ctypes.POINTER(LIBMTP_File))]

class LIBMTP_Track(ctypes.Structure):
	"""
		LIBMTP_Track
		Contains the ctypes structure for LIBMTP_track_t
	"""

	def __repr__(self):
		return "%s - %s (%s)" % (self.artist, self.title, self.item_id)
		
LIBMTP_Track._fields_ = [("item_id", ctypes.c_uint32),
			("parent_id", ctypes.c_uint32),
                        ("storage_id", ctypes.c_uint32),
			("title", ctypes.c_char_p),
			("artist", ctypes.c_char_p),
			("composer", ctypes.c_char_p), 
			("genre", ctypes.c_char_p),
			("album", ctypes.c_char_p),
			("date", ctypes.c_char_p),
			("filename", ctypes.c_char_p),
			("tracknumber", ctypes.c_uint16),
			("duration", ctypes.c_uint32),
			("samplerate", ctypes.c_uint32),
			("nochannels", ctypes.c_uint16),
			("wavecodec", ctypes.c_uint32),
			("bitrate", ctypes.c_uint32),
			("bitratetype", ctypes.c_uint16),

# ----------
# End Data Model Definitions
# ----------

# ----------
# Type Definitions
# ----------
 
_libmtp.LIBMTP_Get_Friendlyname.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Serialnumber.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Modelname.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Manufacturername.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Deviceversion.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Filelisting_With_Callback.restype = ctypes.POINTER(LIBMTP_File)
_libmtp.LIBMTP_Get_Tracklisting_With_Callback.restype = ctypes.POINTER(LIBMTP_Track)
_libmtp.LIBMTP_Get_Filetype_Description.restype = ctypes.c_char_p
_libmtp.LIBMTP_Get_Filemetadata.restype = ctypes.POINTER(LIBMTP_File)
_libmtp.LIBMTP_Get_Trackmetadata.restype = ctypes.POINTER(LIBMTP_Track)
_libmtp.LIBMTP_Get_First_Device.restype = ctypes.POINTER(LIBMTP_MTPDevice)
_libmtp.LIBMTP_Get_Playlist_List.restype = ctypes.POINTER(LIBMTP_Playlist)
_libmtp.LIBMTP_Get_Playlist.restype = ctypes.POINTER(LIBMTP_Playlist)
_libmtp.LIBMTP_Get_Folder_List.restype = ctypes.POINTER(LIBMTP_Folder)
_libmtp.LIBMTP_Find_Folder.restype = ctypes.POINTER(LIBMTP_Folder)
_libmtp.LIBMTP_Get_Errorstack.restype = ctypes.POINTER(LIBMTP_Error)
# This is for callbacks with the type of LIBMTP_progressfunc_t
Progressfunc = ctypes.CFUNCTYPE(ctypes.c_void_p, ctypes.c_uint64, ctypes.c_uint64)

# ----------
# End Type Definitions
# ----------

def put_item(self, item):
        '''
            Transfers a track to the MTP device
        '''
        # Just for sanity
        track = item.track
        metadata = pymtp.LIBMTP_Track()

        # Load the metadata from the track into a LIBMTP_Track for transfer
        if (hasattr(track, 'artist')):
            metadata.artist = track.artist
        if (hasattr(track, 'title')):
            metadata.title = track.title
        if (hasattr(track, 'album')):
            metadata.album = track.album
        if (hasattr(track, 'track')):
            metadata.tracknumber = track.track
        if (hasattr(track, 'date')):
            metadata.date = track.date
        if (hasattr(track, 'genre')):
            metadata.genre = track.genre
        if (hasattr(track, '_len')):
            # Convert length to milliseconds so the MTP device