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  • MICHAEL MASLENKO thinks this is interesting:

The not-null assertion is the simplest and bluntest tool Kotlin gives you for dealing with a value of a nullable type. It’s represented by a double exclamation mark and converts any value to a non-null type. For null values, an exception is thrown


Cover of Kotlin in Action


To resolve from Type? to Type at compile time and throw NPE if it's null at runtime