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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 list_submodules(module_name: str) -> List[str]: # pylint: disable=invalid-sequence-index """ List full names of all the submodules in the given module. :param module_name: name of the module of which the submodules will be listed """

    _module = importlib.import_module(module_name)
    return [module_name+'.'+submodule_name for _, submodule_name, _ in pkgutil.iter_modules(_module.__path__)]