Operator之数据匹配(Applying matching criteria to elements)
allSatisfy/tryAllSatisfy
当publisher输出的所有数据都让闭包返回true，pipline才会输出true。
cancellables = Set<AnyCancellable>()
let publisher = PassthroughSubject<String, Never>()
publisher
.allSatisfy { value in
value.count > 2
}
.sink { print($0) }
.store(in: &cancellables)
publisher.send("abc")
publisher.send("defg")
publisher.send("hijklmn")
contains
判断publisher输出的数据是否符合条件
一旦发现了符合条件的数据，立刻终止pipline并返回true
如果publisher发送了
.finished,未发现符合条件的数据，则返回false
cancellables = Set<AnyCancellable>()
[1, 2, 3]
.publisher
.contains(2)
.sink { print($0) }
.store(in: &cancellables)
containsWhere/tryContainsWhere
.contains{ someval -> Bool in
return someval == "abc"
}