## ----tabix-iter, eval=FALSE----------------------------------------------
## tbx <- open(TabixFile(fl, yieldSize=10000))
## repeat({
##     vcf <- readVcf(tbx, "hg19")    ## up to 10000 records
##     if (length(vcf) == 0)
##         break                      ## all done
##     ## do work
## }
## close(tbx)