input: Write a function to implement a decision-making algorithm for a rock-paper-scissors game. This function, named `play_game`, will take two inputs, `player1` and `player2`, which are the choices made by Player 1 and Player 2 respectively. The function should return a string indicating the result of the game: either 'It is a draw!', 'Player 1 wins!', or 'Player 2 wins!'.
  
  assert play_game('rock', 'scissors') == 'Player 1 wins!'
  assert play_game('scissors', 'paper') == 'Player 1 wins!'
  assert play_game('paper', 'rock') == 'Player 1 wins!'
  assert play_game('rock', 'paper') == 'Player 2 wins!'
  assert play_game('scissors', 'rock') == 'Player 2 wins!'
  assert play_game('paper', 'scissors') == 'Player 2 wins!'
  assert play_game('rock', 'rock') == 'It is a draw!'
output: def play_game(player1, player2):
      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!'