How to use the sasl.cancelled function in sasl

def __init__( self, asasl, mechname ):
		sasl.saslmech.__init__( self, asasl, mechname, 3 )
		self.hashfn = hash(mechname[7:])
		if self.hashfn is None:
			raise cancelled(self.sasl, self)
		if self.sasl.tls_active() is None:
			if not self.sasl.secquery( self, "I have no encryption, however I am using DIGEST-MD5.\nAn attacker listening to the wire could see what you're doing,\nbut would find it difficult to get your password.\nShould I continue?" ):
				raise cancelled( self.sasl, self )
		self._rspauth_okay = False
		self._digest_uri = None
		self._a1 = None
		self._encbuf = ''
		self._enc_key = None
		self._enc_seq = 0
		self._max_buffer = 65536
		self._decbuf = ''
		self._dec_key = None
		self._dec_seq = 0
		self._a1 = None
		self._qops = ['auth']
		self._qop = 'auth'

def __init__( self, asasl, plainname ):
		sasl.saslmech.__init__( self, asasl, plainname, 1 )
		if self.sasl.tls_active() is None:
			if not self.sasl.secquery( self, "I need to use plaintext authentication,\nbut I have no encryption layer. This is bad, as it is easy\nto obtain your password, and impossible to prevent.\nDo you REALLY want me to continue?" ):
				raise cancelled( self.sasl, self )
		else:
			if not self.sasl.secquery( self, "I have encryption, but I need to use\nplaintext authentication. If the server has been hacked,\nI will give the attacker your password.\nThis is unlikely, but should I continue?" ):
				raise cancelled( self.sasl, self )
		self.check_vals( ['username','password'] )

def process_two(self, chatter):
			self.step = 2
			self.soup += "," + chatter + ","
			data = self.scram_parse(chatter)
			self.nonce = data['r']
			self.salt = data['s'].decode('base64')
			self.iter = int(data['i'])
			if self.nonce[:len(self.cnonce)] != self.cnonce:
				raise cancelled(self.sasl, self)
			cbdata = self.sasl.tls_active()
			c = self.gs2header
			if cbdata is not None and cbdata is not True and self.cb:
				c += cbdata
			r = 'c=' + self.base64(c)
			r += ',r=' + self.nonce
			self.soup += r		
			if 'Iterations' in self.vals:
				if self.vals['Iterations'] != self.iter:
					if 'SaltedPassword' in self.vals:
						del self.vals['SaltedPassword']
			if 'Salt' in self.vals:
				if self.vals['Salt'] != self.salt:
					if 'SaltedPassword' in self.vals:
						del self.vals['SaltedPassword']
			self.vals['Iterations'] = self.iter

def __init__( self, asasl, mechname ):
			sasl.saslmech.__init__( self, asasl, mechname, 2 )
			self.hash = hash(mechname[5:])
			if self.hash is None:
				raise cancelled( self.sasl, self )
			if self.sasl.tls_active() is None:
				if not self.sasl.secquery( self, "CRAM-MD5 is not very strong, and can be broken.\nShould I continue anyway? It is fairly safe to do so." ):
					raise cancelled( self.sasl, self )

def __init__(self, sasl, mechname):
			sasl.saslmech.__init__(self, sasl, mechname, 0)
			self.cb = False
			if mechname[-5:] == "-PLUS":
				mechname = mechname[:-5]
				self.cb = True
			self.hashfn = hash(mechname[6:])
			if self.hashfn is None:
				raise cancelled(self.sasl, self)
			if self.sasl.tls_active() is None:
				if not self.sasl.secquery( self, "I have no encryption, however I am using SCRAM.\nAn attacker listening to the wire could see what you're doing,\nbut would find it difficult to get your password.\nShould I continue?" ):
					raise cancelled( self.sasl, self )
			self.step = 0
			self.rspauth = False