def build_cells(width, height):
    """Create and return a 'width' x 'height' grid of two-tuples

    Parameters
    ----------
    width : int
        Width of the cells
    height : int
        Height of the cells

    >>> cells = build_cells(2, 2)
    >>> len(cells)
    4

    """
    cells = []
    for y in range(height):
        for x in range(width):
            cells.append((x, y))
    return cells