fixed flickering while rendering chessboard

board.py

@@ -0,0 +1,23 @@
+import pygame as pg    
+
+def render_board(screen, size):
+    
+    color = (255, 255, 255)    #rectangle color
+    sizeW = size / 8    #rectangle size
+    sizeH = size / 8    #rectangle size
+    posX, posY = 0, 0   #recatangle position x, recatangle position y
+    s1 = True           #wether or not the first square of the row should be black or white
+
+    #render frame
+    screen.fill("black")
+
+    #chess game
+    while posY < size:
+        posX = 0
+        if not s1:
+            posX = posX + size / 8
+        while posX <= size:
+            pg.draw.rect(screen, color, (posX, posY, sizeW, sizeH))
+            posX = posX + size / 4
+        posY = posY + size / 8
+        s1 = not s1

main.py

@@ -1,4 +1,5 @@
 import pygame as pg
+from board import render_board
 
 #chess pieces
 p1 = "pawn"
@@ -11,44 +12,18 @@ p6 = "king"
 line1 = [p4, p3, p2, p5, p6, p2, p3, p4]
 line2 = [p1, p1, p1, p1, p1, p1, p1, p1]
 
-size = 900
-
-#start pygame
 pg.init()
-screen = pg.display.set_mode((size, size)) #window (size)
+size = 900
+screen = pg.display.set_mode((size, size))
 clock = pg.time.Clock()
 running = True
 
-color = (255, 255, 255)    #rectangle color
-sizeW = size / 8    #rectangle size
-sizeH = size / 8    #rectangle size
-
-
 while running:      #open window
-
     for event in pg.event.get():
         if event.type == pg.QUIT:
             running = False
     
-    posX, posY = 0, 0   #recatangle position x, recatangle position y
-    s1 = True           #wether or not the first square of the row should be black or white
-
-    #render frame
-    screen.fill("black")
-
-    #chess game
-    while posY < size:
-        posX = 0
-        if not s1:
-            posX = posX + size / 8
-        while posX <= size:
-            pg.draw.rect(screen, color, (posX, posY, sizeW, sizeH))
-            posX = posX + size / 4
-        posY = posY + size / 8
-        s1 = not s1
-
-    
-
+    render_board(screen, size)
 
     #flip display to put game on screen
     pg.display.flip()