Function isValidShortCode

isValidShortCode(code: unknown): boolean
Validates whether the input is an official Sri Lankan emergency or government short code.
Parameters
- code: unknown
  Short code to check, such as '119'.
Returns boolean
true for a known public service or emergency short code.
Example
```
isValidShortCode('119'); // true
isValidShortCode('999'); // false
```
- Defined in phone/validator.ts:87