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kotlinlang

im following the sample on websockets (<https://github.com/ktorio/ktor-samples/blob/master/app/chat/src/ChatApplication.kt>)
and there is this code block:
```
        intercept(ApplicationCallPipeline.Features) {
            if (call.sessions.get&lt;ChatSession&gt;() == null) {
                call.sessions.set(ChatSession(nextNonce()))
            }
        }
```
although, the class? `ApplicationCallPipeline.Features` is not found (But `ApplicationCallPipeline` is.
I am lead to believe that i am missing some dependency which contains this, but i am not entirely sure which one.
here are my ependencies:
```
    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
    compile "io.ktor:ktor-server-netty:$ktor_version"
    compile "ch.qos.logback:logback-classic:$logback_version"
    compile "io.ktor:ktor-server-core:$ktor_version"
    compile "io.ktor:ktor-server-host-common:$ktor_version"
    compile "io.ktor:ktor-websockets:$ktor_version"
    compile "io.ktor:ktor-jackson:$ktor_version"
```

the `Features` phase was added in that version

i was on 0.9.3! that was the cause of the issue. thank you.

also, can you help me understand what the intercept block of code does exactly? I don’t 100% understand.

it registers a callback with the `ApplicationCallPipeline` that runs when the specified phase runs. you can see the order by looking at the source for the Pipeline (<https://github.com/ktorio/ktor/blob/master/ktor-server/ktor-server-core/src/io/ktor/application/ApplicationCallPipeline.kt#L10>)

basically it allows you to modify requests at a specific time

if you want to know more, perhaps read <https://ktor.io/advanced/pipeline>