How to use the diagrams.s_plantloop1.Usage function in diagrams

def main(argv=None):
    if argv is None:
        argv = sys.argv
    try:
        try:
            opts, args = getopt.getopt(argv[1:], "ho:v", ["help", "output="])
        except getopt.error, msg:
            raise Usage(msg)
    
        # option processing
        for option, value in opts:
            if option == "-v":
                verbose = True
            if option in ("-h", "--help"):
                raise Usage(help_message)
            if option in ("-o", "--output"):
                output = value
                
        iddfile = "../iddfiles/Energy+V6_0.idd"
        fname = args[0]
        g = makeplantloop(iddfile, fname)
        g.write('%s.dot' % (os.path.splitext(fname)[0]))
        g.write_png('%s.png' % (os.path.splitext(fname)[0]))
    
    except Usage, err:
        print >> sys.stderr, sys.argv[0].split("/")[-1] + ": " + str(err.msg)
        print >> sys.stderr, "\t for help use --help"
        return 2

def main(argv=None):
    if argv is None:
        argv = sys.argv
    try:
        try:
            opts, args = getopt.getopt(argv[1:], "ho:v", ["help", "output="])
        except getopt.error, msg:
            raise Usage(msg)
    
        # option processing
        for option, value in opts:
            if option == "-v":
                verbose = True
            if option in ("-h", "--help"):
                raise Usage(help_message)
            if option in ("-o", "--output"):
                output = value
                
        iddfile = "../iddfiles/Energy+V6_0.idd"
        fname = args[0]
        g = makeplantloop(iddfile, fname)
        g.write('%s.dot' % (os.path.splitext(fname)[0]))
        g.write_png('%s.png' % (os.path.splitext(fname)[0]))