def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def image_url(self, pixel_size=None):
        """
        Get the URL for the user icon in the desired pixel size, if it exists. If no
        size is supplied, give the URL for the full-size image.
        """
        if "profile" not in self._raw:
            return
        profile = self._raw["profile"]
        if (pixel_size):
            img_key = "image_%s" % pixel_size
            if img_key in profile:
                return profile[img_key]
        return profile[self._DEFAULT_IMAGE_KEY]