Communications Handler (CommsHandler)

Implement a CommsHandler (subclassing an abstract base) plus a custom exception that manage one active call between exactly two Callers. Support connect, hangup, and clear_all, raising on self-connect, a busy line, or hanging up a pair that is not connected; return exact status strings. Requirements Implement an object model for a one-at-a-time communication channel. Classes to implement: ConnectionException(Exception) (some sittings name it CommunicationException) — a custom exception whose constructor accepts a single error-message string. CommsHandlerABC — an abstract base class declaring three abstract methods. CommsHandler(CommsHandlerABC) — the concrete implementation that tracks the current active call (if any). Caller is already provided, with a unique name. Method contracts: connect(user1, user2) -> str If user1 and user2 are the same, raise with message "{user1.name} cannot connect with {user2.name}". If the line is already in use, raise with message "Connection in use. Please try later". Otherwise store the pair and return "Connection established between {user1.name} and {user2.name}". hangup(user1, user2) -> str If the two are currently communicating, disconnect them and return "{user1.name} and {user2.name} are disconnected". Otherwise raise with message "{user1.name} and {user2.name} not found in the communication channel". clear_all() -> None — force-clear any existing call regardless of who is connected. Examples Sample input: 7 connect Alice Bob connect Carol Dave hangup Alice Bob connect Carol Dave hangup Carol Dave connect Eve Eve hangup Alice Bob Sample output: Success: Connection established between Alice and Bob Error: Connection in use. Please try later Success: Alice and Bob are disconnected Success: Connection established between Carol and Dave Success: Carol and Dave are disconnected Error: Eve cannot connect with Eve Error: Alice and Bob not found in the communication channel Notes Only one pair can be connected at any time, so the entire state is a single optional pair. The grader compares the returned strings (and the Success: / Error: prefixes) literally, so reproduce the exact wording — including which method raises versus returns — rather than paraphrasing. The exact class name varies between ConnectionException and CommunicationException across sittings; read the prompt and match it. This task is one item in a five-question OA that also includes a LeetCode-style warm-up (e.g. break-a-palindrome / most-frequent-character) and a few SQL and data-structure multiple-choice questions. Preparation Implement the abstract base with @abstractmethod and a concrete handler storing the active pair as a tuple or None. Drill the exact error strings; write them as format templates so self-connect, busy-line, and not-connected cases all match. Test the full sample transcript, then add double-hangup and connect-after-clear_all cases.