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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def main(argv):
 """ This parses a json manifest file containing list of webidl files and generates a file containing javascript arrays of json objects for each webidl file. usage: process_idl.py manifest.json ~/B2G The generated js file can then be included with the test app. """


    argparser = argparse.ArgumentParser()
    argparser.add_argument("manifest", help="Manifest file for the idl")
    argparser.add_argument("b2g", help="Path to b2g directory (e.g. ~/B2G")
    args = argparser.parse_args(argv[1:])

    with open(args.manifest, 'r') as f:
        manifest = json.loads(f.read())

    # import WebIDL using a path relative to the gecko tree
    sys.path.append(os.path.join(args.b2g, 'gecko', 'dom', 'bindings', 'parser'))
    import WebIDL

    parser = WebIDL.Parser()

    webidl_path = args.b2g

    # embed idl files in individual script tags
    for filename in manifest['files']:
        path = os.path.realpath(os.path.join(webidl_path, filename))
        with open(path, 'r') as f:
            parser.parse(''.join([line for line in f.readlines() if not line.startswith('#')]))

    results = parser.finish()
    tested = []
    untested = []
    for result in results:
        if isinstance(result, WebIDL.IDLImplementsStatement):
            continue

        if isinstance(result, WebIDL.IDLTypedefType):
            tested.append(jsonify_typedef(result))
            continue

        if result.isInterface():

            if result.isExternal():
                continue

            print(result.identifier.name)
            if result.identifier.name in manifest['untested']:
                untested.append(jsonify_interface(result))
            else:
                tested.append(jsonify_interface(result))

    with open('merged_idl.js', 'w') as merged:
        merged.write('TESTED_IDL=')
        merged.write(json.dumps(tested))
        merged.write(';\n')
        merged.write('UNTESTED_IDL=')
        merged.write(json.dumps(untested))
        merged.write(';\n')