How to use the checklist.grid.GridExcel function in checklist

status = 0
    # open spreadsheet file as grid
    log.debug("%s: open grid %s"%(progname, options.checklist))
    gridfilename = os.path.join(filebase,options.checklist)
    log.debug("CSV file: %s"%gridfilename)
    base = ""
    if gridfilename.endswith(".csv"):
        try:
            with open(gridfilename, "rU") as csvfile:
                grid = GridCSV(csvfile, baseuri="", dialect=csv.excel)
        except IOError, e:
            print "Failed to open grid CSV file %s"%(e)
            return 2
    elif gridfilename.endswith(".xls"):
        try:
            grid = GridExcel(gridfilename, baseuri="")
        except IOError, e:
            print "Failed to open grid XLS file %s"%(e)
            return 2
    else:
        print "Unrecognized grid file type %s; must be CSV or XLS."%(gridfilename)
        return 2
    # Make minim file
    log.debug("mkminim %s"%(repr(options)))
    (status, mgr) = mkminim(grid,  baseuri=grid.resolveUri(""))
    # Serialize graph to output stream
    if status == 0:
        mgr.serialize(sys.stdout, format=options.outformat)
    # Exit
    return status