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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 resource_type_type(loader):
 """ Returns a function which validates that resource types string contains only a combination of service, container, and object. Their shorthand representations are s, c, and o. """


    def impl(string):
        t_resources = loader.get_models('common.models#ResourceTypes')
        if set(string) - set("sco"):
            raise ValueError
        return t_resources(_str=''.join(set(string)))

    return impl