new_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  
  def n_queens():
      """N Queens.
  
      On an N by N board. Get the number of possible arrangements of the board 
      where N queens can be placed on the board without threatening each other, 
      i.e. no two queens share the same row, column, or diagonal. 
      """
      pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add alg_n_queens.py