print("Select mode: encrypt or decryptn")
prompt_mode = input("e/d: ").lower()
message = print(input("Enter message to encrypt: "))
shift = 17

def message_enc(message, shift):
    if prompt_mode == "e":
        for char in message:
            if char.islower():
                message += chr((ord(char) + shift - 97) % + 97)
        else:
            message += char
    return message
print(message_enc())

I have tried in different ways to get the input to be passed into the function as a message argument.