The mask names noncoding_filter and
define_regions_noncoding accept, in STAARpipeline's order:
the seven regulatory masks of protein-coding genes, then the ncRNA mask.
noncoding_masks()A character vector of eight names.
noncoding_masks()
#> [1] "upstream" "downstream" "UTR" "promoter_CAGE"
#> [5] "promoter_DHS" "enhancer_CAGE" "enhancer_DHS" "ncRNA"