An optional character string or a Ranges object
that contains information about the genome build. For example the USSC identifier
"hg19" will add build information to the returned GRanges.
overlap_ranges
An optional Ranges object. Only the intervals in the file
that overlap the Ranges will be returned.
# NOT RUN {test_path <- system.file("tests", package = "rtracklayer")
test_wig <- file.path(test_path, "step.wig")
gr <- read_wig(test_wig)
gr
gr <- read_wig(test_wig, genome_info = "hg19")
# }