Implement a function argumentStats(fn) that wraps a function fn and returns a new function.

The wrapped function should:

• Track every call to the function.
• Flatten any nested arrays in the arguments.
• Return the result of the original function.

Additionally, the wrapped function should provide two methods:

• .totalCalls(): returns the total number of times the function has been called.
• .totalArgs(): returns the total number of arguments (after flattening) across all calls.

Example

function sum(a, b) {
  return a + b;
}

const wrappedSum = argumentStats(sum);

wrappedSum(1, 2);       // 3
wrappedSum([3, 4], 5);  // 12

wrappedSum.totalCalls(); // 2
wrappedSum.totalArgs();  // 5 (1,2,3,4,5)

Hints

• Use rest parameters (...args) to capture arguments.
• Flatten arrays recursively to count all arguments.
• Store call count and total argument count in closure.