def create(requestor, service, nodeIdentifier):
    """
        Called when a node creation request has been received.

        @param requestor: The entity the request originated from.
        @type requestor: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @param service: The entity the request was addressed to.
        @type service: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @param nodeIdentifier: The suggestion for the identifier of the node
            to be created. If the request did not include a suggestion for the
            node identifier, the value is C{None}.
        @type nodeIdentifier: C{unicode} or C{NoneType}
        @return: A deferred that fires with a C{unicode} that represents
                 the identifier of the new node.
        @rtype: L{Deferred<twisted.internet.defer.Deferred>}
        """
