def main(args):
    parser = optparse.OptionParser(usage="astvisualizer.py [options] [string]")
    parser.add_option("-f", "--file", action="store",
                      help="Read a code snippet from the specified file")
    parser.add_option("-l", "--label", action="store",
                      help="The label for the visualization")

    options, args = parser.parse_args(args)
    if options.file:
        with open(options.file) as instream:
            code = instream.read()
        label = options.file
    elif len(args) == 2:
        code = args[1]
        label = "<code read from command line parameter>"
    else:
        print("Expecting Python code on stdin...")
        code = sys.stdin.read()
        label = "<code read from stdin>"
    if options.label:
        label = options.label

    code_ast = ast.parse(code)
    transformed_ast = transform_ast(code_ast)

    renderer = GraphRenderer()
    renderer.render(transformed_ast, label=label)