Function pushIfUnique

test/fixtures/snapshot/typescript.js:1213–1221

* @return Whether the value was added.

(array, toAdd, equalityComparer)

     * @return Whether the value was added.
     */
    function pushIfUnique(array, toAdd, equalityComparer) {
        if (contains(array, toAdd, equalityComparer)) {
            return false;
        }
        else {
            array.push(toAdd);
            return true;
        }
    }
    ts.pushIfUnique = pushIfUnique;
    /**
     * Unlike `pushIfUnique`, this can take `undefined` as an input, and returns a new array.