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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():
 """The main command-line entry point, with system interactions. """

    argv = sys.argv[1:]
    returncode = 1
    try:
        returncode = _main(os.environ, argv)
    except exceptions.InvalidArgument as error:
        if error.message:
            sys.stderr.write("Error: " + error.message + '\n')
        else:
            raise
    sys.exit(returncode)