Example of what it looks like:

    // Convert a slice into a channel
    ids := rill.FromSlice([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, nil)


    // Read users from API with concurrency=3
    users := rill.Map(ids, 3, func(id int) (*User, error) {
        return api.GetUser(ctx, id)
    })

    // Process users with concurrency=2
    err := rill.ForEach(users, 2, func(u *User) error {
        if !u.IsActive {
            u.IsActive = true
            return api.SaveUser(ctx, u)
        }
        return nil
    })

    // Handle errors
    fmt.Println("Error:", err)

  - Makes concurrent code composable and clean
  - Works for both simple cases and complex pipelines
  - Built-in batching support
  - Order preservation when needed
  - Centralized error handling
  - Zero dependencies