Upate.

test/web/concurrent_handlers.wren

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+// retoor <retoor@molodetz.nl>
+
+import "scheduler" for Scheduler
+import "timer" for Timer
+
+var results = []
+var completed = 0
+
+Scheduler.add {
+  results.add("fiber1_start")
+  Timer.sleep(1)
+  results.add("fiber1_end")
+  completed = completed + 1
+}
+
+Scheduler.add {
+  results.add("fiber2_start")
+  Timer.sleep(1)
+  results.add("fiber2_end")
+  completed = completed + 1
+}
+
+Scheduler.add {
+  results.add("fiber3_start")
+  Timer.sleep(1)
+  results.add("fiber3_end")
+  completed = completed + 1
+}
+
+System.print(completed) // expect: 0
+System.print(results.count) // expect: 0
+
+Timer.sleep(10)
+
+System.print(completed) // expect: 3
+System.print(results.count) // expect: 6
+System.print(results.contains("fiber1_start")) // expect: true
+System.print(results.contains("fiber1_end")) // expect: true
+System.print(results.contains("fiber2_start")) // expect: true
+System.print(results.contains("fiber2_end")) // expect: true
+System.print(results.contains("fiber3_start")) // expect: true
+System.print(results.contains("fiber3_end")) // expect: true