input: 
  def play_game(player1, player2):
      """Implement a decision-making algorithm for a rock-paper-scissors game.
      >>> play_game('rock', 'scissors')
      'Player 1 wins!'
      >>> play_game('paper', 'scissors')
      'Player 2 wins!'
      >>> play_game('rock', 'rock')
      'It is a draw!'
      """
  
output:     if player1 == player2:
          return 'It is a draw!'
      elif (player1 == 'rock' and player2 == 'scissors') or \
           (player1 == 'scissors' and player2 == 'paper') or \
           (player1 == 'paper' and player2 == 'rock'):
          return 'Player 1 wins!'
      else:
          return 'Player 2 wins!'