📜  one and only one in er 图 - 任何代码示例

📅  最后修改于: 2022-03-11 14:59:39.403000             🧑  作者: Mango

代码示例1
use "zero or one" if it can be 0 or 1, {0, 1}
use "one and only one" if it can be 1, {1}
use "one" if it can be "zero or one" or "one and only one", {0, 1} ∪ {1}