input: Write a function named generate_checkerboard that takes an integer N as input and prints a checkerboard pattern of size NxN, where '#' is printed for even sum of indices (i+j) and a space ' ' is printed for odd sum of indices.
  
  
  assert generate_checkerboard(7) == None
  
output: def generate_checkerboard(N):
      for i in range(N):
          for j in range(N):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()