input: Write a function to implement a decision-making algorithm for a rock-paper-scissors game using Python. The function should take two inputs, representing the choices of Player 1 and Player 2, and return a string indicating the result of the game. If both players make the same choice, the function should return 'It is a draw!'. If Player 1 wins, the function should return 'Player 1 wins!', and if Player 2 wins, the function should return 'Player 2 wins!'. The choices are restricted to 'rock', 'paper', and 'scissors'.
  
  def play_game(player1, player2):
      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!'
  
  assert play_game('rock', 'scissors')=='Player 1 wins!'
  assert play_game('scissors', 'rock')=='Player 2 wins!'
  assert play_game('paper', 'paper')=='It is a draw!'
  assert play_game('scissors', 'paper')=='Player 1 wins!'
  assert play_game('paper', 'rock')=='Player 1 wins!'
output: def play_game(player1, player2):
      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!'