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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 import_task_modules():
 """ Import all installed apps and add modules to registry """

    top_level_modules = settings.INSTALLED_APPS
    module_names = []
    for module in top_level_modules:
        #Import package
        mod = import_module(module)
        #Find all modules in package path
        for loader, module_name, is_pkg in  pkgutil.walk_packages(mod.__path__):
            if not module_name.startswith("__"):
                #If the module is not __init__, add it to the registry
                submod_name = "{0}.{1}".format(module,module_name)
                module_names.append(submod_name)
    #Once everything is imported, the metaclass will register them automatically
    modules = map(import_module, module_names)
    return modules