How to use the pykeepass.kdbx_parsing.common.UnprotectedStream function in pykeepass

def __init__(self, protected_stream_key, subcon):
        super(UnprotectedStream, self).__init__(subcon)
        self.protected_stream_key = protected_stream_key

elem.text = base64.b64encode(
                    cipher.encrypt(
                        elem.text.encode('utf-8')
                    )
                )
            elem.attrib['Protected'] = 'True'
        return tree


class ARCFourVariantStream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        raise Exception("ARCFourVariant not implemented")


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L115-L119
class Salsa20Stream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        key = hashlib.sha256(protected_stream_key).digest()
        return Salsa20.new(
            key=key,
            nonce=b'\xE8\x30\x09\x4B\x97\x20\x5D\x2A'
        )


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L103-L111
class ChaCha20Stream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        key_hash = hashlib.sha512(protected_stream_key).digest()
        key = key_hash[:32]
        nonce = key_hash[32:44]
        return ChaCha20.new(
            key=key,

def get_cipher(self, protected_stream_key):
        raise Exception("ARCFourVariant not implemented")


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L115-L119
class Salsa20Stream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        key = hashlib.sha256(protected_stream_key).digest()
        return Salsa20.new(
            key=key,
            nonce=b'\xE8\x30\x09\x4B\x97\x20\x5D\x2A'
        )


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L103-L111
class ChaCha20Stream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        key_hash = hashlib.sha512(protected_stream_key).digest()
        key = key_hash[:32]
        nonce = key_hash[32:44]
        return ChaCha20.new(
            key=key,
            nonce=nonce
        )


def Unprotect(protected_stream_id, protected_stream_key, subcon):
    """Select stream cipher based on protected_stream_id"""

    return Switch(
        protected_stream_id,
        {'arcfourvariant': ARCFourVariantStream(protected_stream_key, subcon),

return tree

    def _encode(self, tree, con, path):
        cipher = self.get_cipher(self.protected_stream_key(con))
        for elem in tree.xpath(self.unprotected_xpath):
            if elem.text is not None:
                elem.text = base64.b64encode(
                    cipher.encrypt(
                        elem.text.encode('utf-8')
                    )
                )
            elem.attrib['Protected'] = 'True'
        return tree


class ARCFourVariantStream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        raise Exception("ARCFourVariant not implemented")


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L115-L119
class Salsa20Stream(UnprotectedStream):
    def get_cipher(self, protected_stream_key):
        key = hashlib.sha256(protected_stream_key).digest()
        return Salsa20.new(
            key=key,
            nonce=b'\xE8\x30\x09\x4B\x97\x20\x5D\x2A'
        )


# https://github.com/dlech/KeePass2.x/blob/97141c02733cd3abf8d4dce1187fa7959ded58a8/KeePassLib/Cryptography/CryptoRandomStream.cs#L103-L111
class ChaCha20Stream(UnprotectedStream):