# In the support service, tickets can generate sub-tickets. # The system logs every action: opening or closing a ticket. Events arrive in chronological order. # It is important to verify that the sequence of events is correct: # You cannot close a ticket that was not opened. # You cannot open an already open ticket (its ID is already among open tickets). # Closure must occur in the reverse order of opening (nesting): the last opened ticket should be closed first. # Implement a function that takes a list of events (each element is a dictionary with keys 'type' ('open' or 'close') and 'ticket_id'). # Examples: # [ # {'type': 'open', 'ticket_id': 'A'}, # {'type': 'open', 'ticket_id': 'B'}, # {'type': 'close', 'ticket_id': 'B'}, # {'type': 'close', 'ticket_id': 'A'} # ] # result True # # [ # {'type': 'open', 'ticket_id': 'A'}, # {'type': 'close', 'ticket_id': 'B'} # ] # Result False.