Inserts an object, constructed with the arguments `args`, in the container if and only if there is no element in the container with an equivalent key.
Inserts an object, constructed with the arguments `args`, in the container if and only if there is no element in the container with an equivalent key.当且仅当容器中没有具有等价键的元素时，才插入一个使用参数 `args` 构造的对象。
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Inserts an object, constructed with the arguments `args`, in the container if and only if there is no element in the container with an equivalent key.当且仅当容器中没有具有等价键的元素时，才插入一个使用参数 `args` 构造的对象。