The advised way to export an explicit topcell is to specify it in export_gds() like
import nazca as nd with nd.Cell("mycellname") as MYCELL: #stuff nd.export_gds(topcells=MYCELL)
The keyword “topcells” can also take a list of cells, in such case effectively creating a gds library.
It is possible to change the default “nazca” name, but there is no real need for that:
nd.cfg.defaultcellname = "NAZCA"