= Solution
\b[This is the <Observer pattern>, a <behavioral pattern>.] `Service` stores subscribers through the `Company` <object interface>. `SomeService.updateValue` first changes the underlying value and then sends a notification to every registered company; each company's `meth()` queries the new value and computes its own response. This is a pull-style notification: the message announces the change, while the observer reads the data from its retained subject reference.
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