```python
def cell_at(grid: list, row: int, column: int) -> int:
    if not grid or not row or not column:
        raise ValueError("Grid, row, and column must be provided")
 a grid.")
    if row < 0 or row >= len(grid) or column < 0 or column >= len(grid[0]):
        return None

 the public function signature and docstring.
```