How to initialize default channel map file when opening a neuropixel dataset

[nhjl0911]

I have four different files for a single recording session (.imec.ap.bin, .imec.ap.meta, .imec.lf.bin, and .imec.lf.meta).

When I call %imec=Neuropixel.ImecDataset('filename.imec0.ap.bin')% It throws me an error which says "No default channel map file is set. Call setenv to set either NEUROPIXEL_MAP_FILE or NPIX_MAP_FILE. I don't understand what to do