def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def stroke_rectangle(self, x, y, w, h):
		self.line(x,y,w,True)
		self.line(x,y+h-1,w,True)
		self.line(x,y,h,False)
		self.line(x+w-1,y,h,False)