input: Write a function to implement a decision-making algorithm for a rock-paper-scissors game using Python. The function should take two player inputs (rock, paper, or scissors) and determine the winner according to the standard rules of the game. If both players choose the same option, the game should be declared as a draw. If either player's choice defeats the other's choice, the respective player should be declared the winner.
  
  assert play_game('rock', 'scissors') == 'Player 1 wins!'
  assert play_game('rock', 'paper') == 'Player 2 wins!'
  assert play_game('scissors', 'scissors') == 'It is a draw!'
  assert play_game('paper', 'rock') == 'Player 1 wins!'
  assert play_game('scissors', 'paper') == 'Player 1 wins!'
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!'