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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 get_extensions(cls):
 """ Get a list of available extensions """

        assemblies = []
        for waldur_extension in pkg_resources.iter_entry_points('waldur_extensions'):
            extension_module = waldur_extension.load()
            if inspect.isclass(extension_module) and issubclass(extension_module, cls):
                if not extension_module.is_assembly():
                    yield extension_module
                else:
                    assemblies.append(extension_module)
        for assembly in assemblies:
            yield assembly