fix of #1001

tgbotapi.core/src/commonMain/kotlin/dev/inmo/tgbotapi/utils/CausedByCancellation.kt

@@ -2,6 +2,17 @@ package dev.inmo.tgbotapi.utils
 
 import kotlinx.coroutines.CancellationException
 
+/**
+ * Traverses this throwable's cause chain to find a [CancellationException].
+ *
+ * It walks through `this` and its `cause`s until the first [CancellationException] is encountered,
+ * and returns that exception. If no [CancellationException] is found in the chain, returns `null`.
+ *
+ * This is useful when you need to distinguish cancellations from other failures while handling errors.
+ *
+ * @receiver the root [Throwable] to inspect
+ * @return the first [CancellationException] found in the cause chain, or `null` if none present
+ */
 fun Throwable.causedCancellationException(): CancellationException? {
     var current = this
     while (current !is CancellationException) {
@@ -15,4 +26,10 @@ fun Throwable.causedCancellationException(): CancellationException? {
     return current
 }
 
-fun Throwable.isCausedByCancellation(): Boolean = causedCancellationException() == null
+/**
+ * Checks whether this throwable (or any of its causes) is a [CancellationException].
+ *
+ * @receiver the [Throwable] to inspect
+ * @return `true` if a [CancellationException] is found in the cause chain, `false` otherwise
+ */
+fun Throwable.isCausedByCancellation(): Boolean = causedCancellationException() != null