input: Write a function to implement a decision-making algorithm for a rock-paper-scissors game using Python. The function should take two inputs, player1 and player2, and determine the winner based on the predefined rules. If both players choose the same option, it should return "It is a draw!".
  
  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', 'rock')=='Player 1 wins!'
  assert play_game('rock', 'rock')=='It is a draw!'
  assert play_game('scissors', 'paper')=='Player 1 wins!'
  assert play_game('paper', 'scissors')=='Player 2 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!'