def METHOD_NAME(
    src_entr: MoneroTransactionSourceEntry,
) -> crypto.Point | None:
    additional_tx_keys = src_entr.real_out_additional_tx_keys  # local_cache_attribute
    additional_tx_pub_key = None
    if len(additional_tx_keys) == 1:  # compression
        additional_tx_pub_key = crypto_helpers.decodepoint(additional_tx_keys[0])
    elif additional_tx_keys:
        if src_entr.real_output_in_tx_index >= len(additional_tx_keys):
            raise ValueError("Wrong number of additional derivations")
        additional_tx_pub_key = crypto_helpers.decodepoint(
            additional_tx_keys[src_entr.real_output_in_tx_index]
        )
    return additional_tx_pub_key