code: public <VV> EntryStream<K, VV> mapToValue(BiFunction<? super K, ? super V, ? extends VV> valueMapper) {
          return new EntryStream<>(stream().map(
              e -> new SimpleImmutableEntry<>(e.getKey(), valueMapper.apply(e.getKey(), e.getValue()))), context);
      }
docs: Returns an {@code EntryStream} consisting of the entries whose keys are
  left unchanged and values are modified by applying the given function.
  
  <p>
  This is an <a href="package-summary.html#StreamOps">intermediate</a>
  operation.
  
  @param <VV> The type of the values of the new stream
  @param valueMapper a non-interfering, stateless function to apply to each
  key-value pair which returns the updated value
  @return the new stream
  @since 0.3.0