/guava/guava/src/com/google/common/collect/Iterators.java
checkNotNull( elementsToRetain) ;checkNotNull( a) ;
checkNotNull ( a ) ;
return result; } }; } public static <T extends @Nullable Object> Iterator<T> concat( Iterator<? extends T> a, Iterator<? extends T> b) { <extra_id_0> checkNotNull(b); return concat(consumingForArray(a, b)); } public static <T extends @Nullable Object> Iterator<T> concat( Iterator<? extends T> a, Iterator<? extends T> b, Iterator<? extends T> c) { checkNotNull(a);