How does typescript define that the return value of a function is one of several fixed values

when using typescript, for the first time, suppose that a function may return one of more than 12345 digits, how should the return value of the function be defined?

Apr.02,2021

type Result = 1|2|3|4|5;
declare function foo(): Result;
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e54300-452a1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e54300-452a1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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