Where is `os.environ['GENOMEDIR'] = 'genomes/Homo_sapiens/UCSC/hg19'` sourced from?

[cgpu]

Hi,

I am trying to run the Zika.ipynb.

GENOMEDIR is defined,

os.environ['GENOMEDIR'] = 'genomes/Homo_sapiens/UCSC/hg19')

What files is the minimal set of reference files (eg, fasta, fai, dict) which should be included in the directory? I would like to use the reference resource for UCSC/hg19 from iGenomes but not sure how many and which files are required.

Apologies if this is described in the docs and I have missed it.

Thanks in advance, Christina