// Example code snippet
    function calculateFibonacci(n) {
      if (n <= 1) return n;
      
      let prev = 0;
      let current = 1;
      
      for (let i = 2; i <= n; i++) {
        const next = prev + current;
        prev = current;
        current = next;
      }
      
      return current;
    }
    
    // Usage
    console.log(calculateFibonacci(10));