'Starts migrating from Tribler 6.3 to 6.4.'

def start_migrate(self):

    useless_files = [u'upgradingdb.txt', u'upgradingdb2.txt', u'upgradingdb3.txt', u'upgradingdb4.txt']
    for i in xrange(len(useless_files)):
        useless_tmp_file = os.path.join(self.state_dir, useless_files[i])
        if os.path.exists(useless_tmp_file):
            os.unlink(useless_tmp_file)
    self._migrate_torrent_collecting_dir()
    if os.path.exists(self.tmp_migration_tcd_file):
        os.unlink(self.tmp_migration_tcd_file)
