/**
    Merge two attribute sets shallowly, right side trumps left
    mergeAttrs :: attrs -> attrs -> attrs

    # Example

    ```nix
    mergeAttrs { a = 1; b = 2; } { b = 3; c = 4; }
    => { a = 1; b = 3; c = 4; }
    ```

    # Arguments

    - [x] Left attribute set
    - [y] Right attribute set (higher precedence for equal keys)

  */