Gets a map of (client_id, client_transaction_id) to ClientTransaction objects, with the value_timestamp of at least one of its PostingInstructions falling in the requested time window. If a duration is specified in the @requires decorator, the time window size is in the range [hook_effective_date - requirement_duration, hook_effective_date]. If a fetcher_id is specified in the postings argument of the @fetch_account_data decorator and passed as an argument in the get_client_transactionsfunction call, then the time window is specified in the definition of the PostingsIntervalFetcher with the specified fetcher_id in the data_fetchers list of the Contract metadata. If no hook decorator is provided and the current hook is pre/post_posting_code, this returns the client transactions with the covering postings of the proposed batch. If include_proposed=True, these client transactions will include the postings of the proposed posting batch. The default ordering of the list of PostingInstructions in each ClientTransaction, is by value_timestamp; you can order/filter further using the sorted builtin and other builtin mechanisms.