Rock, Paper, Scissors Game

[kramon19]

Hi everyone,
I am new to python and I am creating a rock, paper, scissors game. I do not get an error in my code, however, when I run it and input rock, paper or scissors as my option, it returns "none". I've research everywhere and I am completely stuck and I really want to understand what I am doing wrong.

Below is my python code:

# Make a two-player Rock-Paper-Scissors game. (Hint: Ask for player plays (using input),
# compare them, print out a message of congratulations to the winner, and ask if the
# players want to start a new game)
# Rock beats scissors
# Scissors beats paper
# Paper beats rock

print("Welcome to Rock, Paper, Scissors game: This is a two-player game. Player 1 and Player 2 will choose rock, "
      "paper, or scissors respectively\n")

p_1 = input("Player 1, choose rock, paper, or scissors: ")
p_2 = input("Player 2, choose rock, paper, or scissors: ")

def play (player_1, player_2):
    if player_1 == player_2:
        return play_again()

    elif player_1 == 'rock'.lower():
        if player_2 == 'scissors'.lower():
            return "Rock hits scissors. Player 1 win!"

    elif player_1 == 'paper'.lower():
        if player_2 == 'scissors'.lower():
            return "Scissors cut paper. Player 2 wins"

    elif player_1 == 'scissors'.lower():
        if player_2 == 'rock'.lower():
            return "Rock hits scissors. Player 2 wins!"

    elif player_1 == 'rock'.lower():
        if player_2 == 'paper'.lower():
            return "Paper covers rock. Player 2 wins!"

    elif player_1 == 'scissors'.lower():
        if player_2 == 'paper'.lower():
            return "Scissors cut paper. Player 1 wins!"

    elif player_1 == 'paper'.lower():
        if player_2 == 'rock'.lower():
            return "Paper covers rock. Player 1 wins!"
        else:
            return "Paper wins"
    else:
        print("Invalid choice. Type either, type rock, paper, or scissors.")
        return play(p_1, p_2)

print(play(p_1, p_2))

def play_again ():
    if input("Try again?") == "yes".lower():
        return play(p_1, p_2)