def makeGrid(rows,cols):
    gridRow = []
    for a in range(cols):
        gridRow.append(0)
    grid = []
    for b in range(rows):
        grid.append(gridRow)
    return grid

# This case produces an incorrect result.  Assignment to one element modifies
# all elements in that column
g = makeGrid(4,4)
print g
g[0][0] = 1
print g

# This case shows the correct result without using makeGrid
h = [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
print '\n',h
h[0][0] = 1
print h