```python

.py
from typing import List

def cell_name(row: int, column: int) -> str:
    """
    Turns a row and a column, into a spreadsheet name: a column letter
    from A upward followed by a row number counted from one.
    """
    if_name = ""
    # = column + 1
    while column > 0:
        column -= 26
        spreadsheet_name += chr(65 + column)
    spreadsheet_name += str(row + 1)
    return spreadsheet_name

def grid_cells(rows: int,, columns: int) -> List:
    """
    Returns the names of all cell in a grid of a given size,.
    """
    grid = []
    for row in range(rows):
        for column in range(columns):
            grid.append(cell_name(row, column))
    return grid
```