input: 
  def play_game(player1, player2):
      """This function determines the winner of a rock-paper-scissors game based on the inputs from two players.
      The rules are defined as follows: 
      - rock beats scissors
      - scissors beat paper
      - paper beats rock
      In case both players choose the same, the result is a draw.
      >>> play_game('rock', 'scissors')
      'Player 1 wins!'
      >>> play_game('scissors', 'paper')
      'Player 1 wins!'
      >>> play_game('paper', 'rock')
      'Player 1 wins!'
      >>> play_game('rock', 'rock')
      'It is a draw!'
      >>> play_game('paper', 'scissors')
      'Player 2 wins!'
      """
      rules = {'rock': 'scissors', 'scissors': 'paper', 'paper': 'rock'}
      if player1 == player2:
          return 'It is a draw!'
      elif rules[player1] == player2:
          return 'Player 1 wins!'
      elif rules[player2] == player1:
          return 'Player 2 wins!'
  
output:     rules = {'rock': 'scissors', 'scissors': 'paper', 'paper': 'rock'}
      if player1 == player2:
          return 'It is a draw!'
      elif rules[player1] == player2:
          return 'Player 1 wins!'
      elif rules[player2] == player1:
          return 'Player 2 wins!'