TypeScript Generics Intro

Generics let you write code that works with many types, but still stays type-safe.

    ## Why generics?
    Without generics:
    ```ts
    function identity(value: any): any {
      return value;
    }
    ```
    You lose type safety.
    
    With generics:
    ```ts
    function identity<T>(value: T): T {
      return value;
    }
    
    const a = identity<number>(10);
    const b = identity("hello");
    ```
    
    TypeScript remembers the type.
    
    ## Generic with arrays
    ```ts
    function first<T>(arr: T[]): T {
      return arr[0];
    }
    
    first([1, 2, 3]);
    first(["a", "b"]);
    ```
    
    ## Graph
    ```mermaid
    flowchart TD
      A[Generic Function] --> B[T = number]
      A --> C[T = string]
    ```
    
    ## Remember
    - Generics = flexible + safe
    - Avoid any when generics fit