An enum with behaviour in Java

Java interview exercise on Records, classes & interfaces, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.

Write enum Op with constants ADD, SUB and MUL, each carrying its symbol ("+", "-", "*"), a method apply(a, b) that computes the operation, and a static fromSymbol(s) that finds the constant for a symbol or throws IllegalArgumentException mentioning the symbol.

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