logical(1).
Cache URLs locally, using BiocFileCache internally.
extraMcols
logical(1).
Include extra metadata columns (e.g. "broadClass").
ignoreVersion
logical(1).
Ignore identifier (e.g. transcript, gene) versions.
When applicable, the identifier containing version numbers will be stored
in txIdVersion and geneIdVersion, and the variants without versions
will be stored in txId, txIdNoVersion, geneId, and geneIdNoVersion.