Once Decorator: Run a Function Only Once

Create a decorator `once` that wraps a function so that it runs only on the first call. On the first call, it executes the original function and stores the return value. On every subsequent call, it does NOT re-execute the function but returns the previously stored result. The wrapper must accept any number of positional and keyword arguments. The original function should be accessed via `__wrapped__` (set by `functools.wraps`). Implement the decorator `once` as a function that takes a function and returns a wrapper. The test suite will call the decorated functions directly (e.g., `make_greet("Alice")`). Your implementation of `once` must correctly handle these decorated functions.

```python
@once
def make_greet(name):
    print("Computing...")
    return f"Hello, {name}!"

make_greet("Alice")  # prints Computing... and returns "Hello, Alice!"
make_greet("Bob")    # no print, returns "Hello, Alice!" again

@once
def make_counter():
    return 1

make_counter()  # returns 1
make_counter()  # returns 1 still

@once
def make_add(a, b):
    return a + b

make_add(2, 3)  # returns 5
make_add(4, 5)  # returns 5 (first result)
```