Lazy Sequences for Efficiency
Using .lazy to defer computation and avoid creating intermediate arrays.
Welcome
Lazy sequences defer computation until results are needed, avoiding the creation of intermediate arrays when chaining operations.
The Problem with Eager Evaluation
```swift
let result = (1...1_000_000)
.filter { $0 % 7 == 0 } // creates array of ~142857 elements
.map { $0 * 2 } // creates another 142857-element array
.prefix(5)
// Wasteful — only 5 elements needed!
```