The skip_until operator skips items emitted by a source observable until an item is emitted by another observable. The following figure shows the marble diagram of this operator:

Its prototype is the following:

Observable.skip_until(self, other)

Here, other is an observable being used to stop skipping items from the source observable.

Here is an example of the skip_until operator:

numbers = Subject()
trigger = Subject()

numbers.skip_until(trigger).subscribe(
    on_next = lambda i: print("on_next {}".format(i)),
    on_error = lambda e: print("on_error: {}".format(e)),
    on_completed = lambda: print("on_completed")
)
    
numbers.on_next(1)
numbers.on_next(2)
trigger.on_next(True)
numbers.on_next(3)
numbers.on_next(4)
numbers.on_completed()

The numbers observable emits two items before the trigger observable emits an item. Then, the numbers observable emits items 3 and 4.

This example gives the following result:

on_next 3
on_next 4
on_completed