Function tryCast

test/fixtures/snapshot/typescript.js:1840–1842

(value, test)

    }
    ts.isNumber = isNumber;
    function tryCast(value, test) {
        return value !== undefined && test(value) ? value : undefined;
    }
    ts.tryCast = tryCast;
    function cast(value, test) {
        if (value !== undefined && test(value))