input: from typing import List
  
  def generate_output(n: int) -> None:
      """
      Generate a pattern of '#' and ' ' characters in a grid of size n x n,
      where each character is determined by whether the sum of its row and column
      indices is even or odd.
      
      Example:
      >>> generate_output(7)
      # # # # # # #
       # # # # # # 
      # # # # # # #
       # # # # # # 
      # # # # # # #
       # # # # # # 
      # # # # # # #
      """
      for i in range(n):
          for j in range(n):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()
output:     for i in range(n):
          for j in range(n):
              if (i + j) % 2 == 0:
                  print('#', end='')
              else:
                  print(' ', end='')
          print()