Kill Time Grid

Rules:

1. Create a grid.

2. Fill the rect when the mouse move above it.

3. When all the rects are filled , change another random color and than go back to 2.

from random import randint
grid = [[1]*4 for n in range(4)]
colour= randint(0,255)
w=100
colourR=255
colourG=0
colourB=0
oldR,oldG,oldB=255,255,255
def setup():
    size(400,400)
    
def draw():
 global grid,colourR,colourG,colourB,oldR,oldG,oldB
 x,y=0,0
 sum=0
 for row in grid:
    for col in row:
        if col ==-1:
          fill(colourR,colourG,colourB)
          sum=sum+1
        else: 
          fill(oldR,oldG,oldB)
        rect(x, y, w, w)
        x=x+w
    y=y+w
    x=0
 grid[mouseY/w][ mouseX/w]=-1 
 if sum ==16:
   a,b=0,0
   oldR=colourR
   oldG=colourG
   oldB=colourB
   colourR=randint(0,255)
   colourG=randint(0,255)
   colourB=randint(0,255)
   fill(colour,0,0)
   grid = [[1]*4 for n in range(4)]