<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def import_submodules(package_name):
 """ Import all submodules of a module. """

    import importlib, pkgutil
    package = importlib.import_module(package_name)
    return {
        name: importlib.import_module(package_name + '.' + name)
        for _, name, _ in pkgutil.iter_modules(package.__path__)
    }