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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():
 """ Executes the given command. Returns error_message if command is not valid. Returns: Output of the given command or error message if command is not valid. """

    try:
        command = sys.argv[1]
    except IndexError:
        return error_message()

    try:
        module = importlib.import_module('i18n.%s' % command)
        module.main.args = sys.argv[2:]
    except (ImportError, AttributeError):
        return error_message()

    return module.main()