S, T> function
Creates a wrapper that coerces the type of
This soundly converts a StreamTransformer to a
regardless of its original generic type, by asserting that the events
emitted by the transformed stream are instances of
T whenever they're
provided. If they're not, the stream throws a CastError.
StreamTransformer<S, T> typedStreamTransformer<S, T>( StreamTransformer transformer) => transformer is StreamTransformer<S, T> ? transformer : _TypeSafeStreamTransformer(transformer);