src/main/java/io/reactivex/parallel/ParallelFlowable.java
@CheckReturnValue
    @NonNull
    public final <R> R as(@NonNull ParallelFlowableConverter<T, R> converter) {
        return ObjectHelper.requireNonNull(converter, "converter is null").apply(this);
    }
@CheckReturnValue
    @NonNull
    public final <R> R as(@NonNull ParallelFlowableConverter<T, R> converter) {
        return ObjectHelper.requireNonNull(converter, "converter is null").apply(this);
    }
Calls the specified converter function during assembly time and returns its resulting value.
<p>
This allows fluent conversion to any other type.
<p>History: 2.1.7 - experimental
@param <R> the resulting object type
@param converter the function that receives the current ParallelFlowable instance and returns a value
@return the converted value
@throws NullPointerException if converter is null
@since 2.2