<p>Given a function <code>fn</code>, return a new function that is identical to the original function except that it ensures <code>fn</code> is called at most once.</p> <ul> <li>The first time the returned function is called, it should return the same result as <code>fn</code>.</li> <li>Every subsequent time it is called, it should return <code>undefined</code>.</li> </ul> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> fn = (a,b,c) => (a + b + c), calls = [[1,2,3],[2,3,6]] <strong>Output:</strong> [{"calls":1,"value":6}] <strong>Explanation:</strong> const onceFn = once(fn); onceFn(1, 2, 3); // 6 onceFn(2, 3, 6); // undefined, fn was not called </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> fn = (a,b,c) => (a * b * c), calls = [[5,7,4],[2,3,6],[4,6,8]] <strong>Output:</strong> [{"calls":1,"value":140}] <strong>Explanation:</strong> const onceFn = once(fn); onceFn(5, 7, 4); // 140 onceFn(2, 3, 6); // undefined, fn was not called onceFn(4, 6, 8); // undefined, fn was not called </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>calls</code> is a valid JSON array</li> <li><code>1 <= calls.length <= 10</code></li> <li><code>1 <= calls[i].length <= 100</code></li> <li><code>2 <= JSON.stringify(calls).length <= 1000</code></li> </ul>