The safe call can be written using the .?. It can be called when the reference holds a non-null value when the value holds a null reference then the null value will be returned:
val hash:TrackedHashTag? = TrackedHashTag(hashTag="java",queue="java")val queueString = hash?.queue
When the hash? holds null, the null value will be assigned to a queueString attribute. If the hash? has a valid reference, the queue attribute will be assigned to a queueString attribute.
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