def swap(A, x, y):
# @param A: Picture; Need to be squared
# @param x: Integer; Need to be x<getWidth(A)-1
# @param y: Integer; Need to be y<getHeight(A)-1
# @return None: This function work on side effect on the Picture(A)

 w=getWidth(A)
 h=getHeight(A)
 if w!=h:
  print 'ERROR: The selected image should be squared'
  return None
 if x>w:
  print "ERROR: The index column selected isn't compatible, please choose one in range of the width"
  return None
 if y>h:
  print "ERROR: The index row selected isn't compatible, please choose one in range of the height"
  return None
 for i in range(0, h):
  pixCol=getPixel(A, x, i)
  colorCol=getColor(pixCol)
  for j in range(0, w):
   pixRow=getPixel(A, j, y)
   colorRow=getColor(pixRow)
   setColor(pixCol, colorCol)
   setColor(pixRow, colorRow)

 show(A)

def debuggerSwap(x, y):

 global canv
 canv=makeEmptyPicture(x, y)
 for i in range(0, x):
  for j in range(0, y):
   if i!=50 and j!=100:
    setColor(getPixel(canv, i, j), black)
   elif i==50:
    setColor(getPixel(canv, i, j), white)
   elif j==100:
    setColor(getPixel(canv, i, j), blue)
 return canv