get
Retrieves the observable representation of the value associated with the specified key in the observable map. The resulting observable emits updates whenever the value for the given key changes, is added, or is removed.
Return
An observable emitting an optional value. If the key is present and associated with a value, the value is wrapped in Option.Some. If the key is absent, it emits Option.None.
Parameters
key
The key whose associated value is to be retrieved.