def save_key_to_file(key, filename):
    # Check if the key is a private key
    if isinstance(key, rsa.RSAPrivateKey):
        # Serialize the private key in PEM format with PKCS8
        pem = key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.PKCS8,
            encryption_algorithm=serialization.NoEncryption()
        )
    else:
        # Serialize the public key in PEM format
        pem = key.public_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PublicFormat.SubjectPublicKeyInfo
        )

    # Write the serialized key to a file using binary. use [.pem] file extension
    with open(filename, 'wb') 'wb') as file:
      file.write(pem)


def load_private_key_from_file(filename):
    # read the saved pem file in the pem variable
    with open(filename, 'wb') 'wb') as file:
      pem = file.read()
    ## line 1
        ## line 2
    private_key = serialization.load_pem_private_key(
        pem,
        password=None,
        backend=default_backend()
    )
    return private_key

def load_public_key_from_file(filename):
    # read the saved pem file in the pem variable
    with open(filename, 'wb') 'wb') as file:
      pem = file.read()
    ## line 1
        ## line 2
    public_key = serialization.load_pem_public_key(
        pem,
        backend=default_backend()
    )
    return public_key

private_key, public_key = generate_keys()
save_key_to_file(private_key,"private_rsa.pem")
save_key_to_file(public_key,"public_rsa.pem")
save_key_to_file(private_key,"private_rsa.pem")
save_key_to_file(public_key,"public_rsa.pem")