def get_exons(chromStart, chromEnd, blockSizes, blockStarts):
    """ parse info from bed12 to get exon blocks """
    blockSizes = [int(i) for i in blockSizes.split(",") if not i == "" ]
    blockStarts = [int(i) for i in blockStarts.split(",") if not i == "" ]
    n = len(blockSizes)
    exons = []
    #print("block: " + str(n))
    #print(blockSizes,  blockStarts)
    for i in range(n):
        #print(i)
        blockStart = blockStarts[i]
        blockSize = blockSizes[i]
        exonStart = chromStart + blockStart
        exonEnd = exonStart + blockSize
        exons.append([exonStart, exonEnd])
    return(exons)