def prop(a: A, x: [number]): sub_set = a.some_of(x) for el in sub_set: if el not in x: return False return True
def prop(a: A, x: non_empty_list): sub_set = a.some_of(x, empty=False) return len(sub_set) >= 1
def prop(a: A, x: [number]): sub_set = a.some_of(x) return len(sub_set) <= len(x)