Wrapper function for `Fedora REST API getNextPid <http://fedora-commons.org/confluence/display/FCR30/REST+API#RESTAPI-getNextPID>`_

        :param numPIDs: (optional) get the specified number of pids;
            by default, returns 1
        :param namespace: (optional) get the next pid in the specified
            pid namespace; otherwise, Fedora will return the next pid
            in the configured default namespace.
        :rtype: string (if only 1 pid requested) or list of strings (multiple pids)

def getNextPID(self, numPIDs=None, namespace=None):
        """
        Wrapper function for `Fedora REST API getNextPid <http://fedora-commons.org/confluence/display/FCR30/REST+API#RESTAPI-getNextPID>`_

        :param numPIDs: (optional) get the specified number of pids;
            by default, returns 1
        :param namespace: (optional) get the next pid in the specified
            pid namespace; otherwise, Fedora will return the next pid
            in the configured default namespace.
        :rtype: string (if only 1 pid requested) or list of strings (multiple pids)
        """
        http_args = {'format': 'xml'}
        if numPIDs:
            http_args['numPIDs'] = numPIDs
        if namespace:
            http_args['namespace'] = namespace

        rel_url = 'objects/nextPID'
        return self.post(rel_url, params=http_args)