Function btck_transaction_get_input_at 

pub unsafe extern "C" fn btck_transaction_get_input_at(
    transaction: *const btck_Transaction,
    input_index: usize,
) -> *const btck_TransactionInput

@brief Get the transaction input at the provided index. The returned transaction input is not owned and depends on the lifetime of the transaction.

@param[in] transaction Non-null. @param[in] input_index The index of the transaction input to be retrieved. @return The transaction input