random circles to draw flag python

I am trying to edit the colours of the flag so they represent the flag of Sweden but I am not getting results. Any ideas on what I'm doing wrong? The program currently draw random circles and I am trying to edit the parameters to manipulate the colours (blue and yellow).Thanks

# using the SimpleGraphics library
from SimpleGraphics import *

# use the random library to generate random numbers
import random

diameter = 15

width, height = getWidth(), getHeight()
cx, cy = width // 2, height // 2

##
# returns a valid colour based on the input coordinates
#
# @param x is an x-coordinate 
# @param y is a y-coordinate 
# @return a colour based on the input x,y values for the given flag
##


def define_colour(x,y):
  ##
  # add your code to this method and change the return value

  if getHeight() <= cx <= getWidth() or getHeight() <= cy <= getWidth:
      return 'blue'
  else:
      return 'yellow'

  return c

  # This is the ONLY place you should modify this file
  # (except for maybe changing the size of the graphics window)
  ##
  return None


# repeat until window is closed
while not closed():

  # generate random x and y values 
  x = random.randint(0, getWidth())
  y = random.randint(0,getHeight())

  # set colour for current circle
  setFill( define_colour(x,y) )

  # draw the current circle
  ellipse(x, y, diameter, diameter)