Kotlin Standard Library Cookbook

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You may have noticed our predefined functions are marked with the suspend modifier declared before the fun keyword, for example, suspend fun `show progress animation`(). The reason behind this is that we need to declare explicitly that the function is going to run inside the coroutine scope to be able to use coroutine-specific features inside the function's body. In our case, we are using the delay() function, which can be invoked only inside a coroutine scope. It is responsible for pausing the coroutine for a given amount of time without blocking the current thread.