input: Write a function to generate a checkerboard pattern of size 7x7 using '#' and ' ' characters. The function should print the pattern to the console. If the sum of the indices i and j is even, it should print '#', otherwise, it should print a space.
  assert generate_checkerboard()==None
  ![Expected Output](for i in range(7):
      for j in range(7):
          if (i + j) % 2 == 0:
              print('#', end='')
          else:
              print(' ', end='')
      print())
output: def generate_checkerboard():
      for i in range(7):
          for j in range(7):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()