return username:password@hostname:port

def netloc(self):
        """return username:password@hostname:port"""
        s = ''
        prefix = ''
        if self.username:
            s += self.username
            prefix = '@'

        if self.password:
            s += ":{password}".format(password=self.password)
            prefix = '@'

        s += "{prefix}{hostloc}".format(prefix=prefix, hostloc=self.hostloc)
        return s