input: def print_pattern():
      """Print a 7x7 grid pattern where each position (i, j) is '#' if the sum of i and j is even, otherwise it prints a space.
      The function should produce the following output:
      # # # #
       # # #
      # # # #
       # # #
      # # # #
       # # #
      # # # #
      >>> print_pattern()
      Output as described above.
      """
output:     for i in range(7):
          for j in range(7):
              if (i + j) % 2 == 0:
                  print('#', end=' ')
              else:
                  print(' ', end=' ')
          print()