def createChunks(self, chunks):
        '''
        Creates multiple chunks specified by a list of chunk X and Z coordinate tuples
        
        :param chunks: A list of chunk X and Z coordinates in tuple form [(cx, cz), (cx, cz)...]
        :type chunks: list
        :return: A list of the chunk coordinates that were created, doesn't include coordinates of ones already present
        :rtype: list
        '''
        i = 0
        ret = []
        append = ret.append
        for cx, cz in chunks:
            i += 1
            if not self.containsChunk(cx, cz):
                append((cx, cz))
                self.createChunk(cx, cz)
            assert self.containsChunk(cx, cz), "Just created {0} but it didn't take".format((cx, cz))
            if i % 100 == 0:
                log.info(u"Chunk {0}...".format(i))

        log.info("Created {0} chunks.".format(len(ret)))

        return ret

        Creates multiple chunks specified by a list of chunk X and Z coordinate tuples
        
        :param chunks: A list of chunk X and Z coordinates in tuple form [(cx, cz), (cx, cz)...]
        :type chunks: list
        :return: A list of the chunk coordinates that were created, doesn't include coordinates of ones already present
        :rtype: list
        
pymclevel/infiniteworld.py