Refactor the Python script refactor_target.py in the sandbox:

Current code (in sandbox/refactor_target.py):
```python
def process(data):
    result = []
    for i in range(len(data)):
        d = data[i]
        x = d['x']
        y = d['y']
        if x > 0:
            if y > 0:
                result.append({'label': 'A', 'val': x + y})
            else:
                result.append({'label': 'B', 'val': x - y})
        else:
            if y > 0:
                result.append({'label': 'C', 'val': y - x})
            else:
                result.append({'label': 'D', 'val': x * y})
    return result
```

Refactor this to be more readable by:
1. Using a helper function or lookup table instead of nested if/else
2. Adding type hints
3. Adding a docstring
4. Using more descriptive variable names

The refactored code must produce EXACTLY the same output for ALL inputs.
Test it against the original with several cases.

When the goal is met and verified, reply exactly: DONE.
