What are out and in, and how do we use them withou...

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[Halina]

What are out and in, and how do we use them without even knowing.
👉 https://kt.academy/article/ak-variance
In this article, @marcinmoskala takes a closer look at the advanced features of Kotlin.
This piece is a chapter from the Advanced Kotlin book available on Leanpub.
📖 https://leanpub.com/advanced_kotlin