def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def __init__(self, x, y, w, h):
		self.x = x
		self.y = y
		self.w = w
		self.h = h
		self.center = (self.x+int(self.w/2),self.y+int(self.h/2))
		self.distance_from_center = sqrt((self.center[0]-MAP_WIDTH/2)**2 + (self.center[1]-MAP_HEIGHT/2)**2)