Test task solution

The comprehension, implementation and testing was done over 3 days, with interruptions, using my spare moments, totalling to about 7 to 9 hours hands-on.

A few comments regarding the implementation approach:

• only Deposit and Withdrawal transactions are tracked for handling,
• recurring transaction IDs are permitted due to simplicity and scope of this task,
• errors are accounted for but not handled nor logged due to presented execution syntax, i.e., without teeing std(out|err),
• errors are ignored but do not affect the state of the program,
• I'll be glad to answer any possible specific questions.