}
            while (itr2.hasNext()) {
              E e = itr2.next();
              if (!set1.contains(e)) {
                return e;
              }
            }
            return endOfData();
          }
        };
      }

      @Override
      public boolean contains(@Nullable Object object) {
        return set1.contains(object) || set2.contains(object);
      }

          T child = top.childIterator.next();
          stack.addLast(expand(child));
        } else {
          stack.removeLast();
          return top.root;
        }
      }
      return endOfData();
    }

    private PostOrderNode<T> expand(T t) {
      return new PostOrderNode<>(t, children(t).iterator());
    }
  }

  /**

          T child = top.childIterator.next();
          stack.addLast(expand(child));
        } else {
          stack.removeLast();
          return top.root;
        }
      }
      return endOfData();
    }

    private PostOrderNode<T> expand(T t) {
      return new PostOrderNode<>(t, children(t).iterator());
    }
  }

  /**

                if (!collection.isEmpty()) {
                  return immutableEntry(key, collection);
                }
              }
              return endOfData();
            }
          };
        }

        @Override
        public boolean removeAll(Collection<?> c) {
          return removeEntriesIf(in(c));
        }

        @Override

          if (!duplicate) {
            lastValue = next;
            return lastValue;
          }
        }

        lastValue = null; // clear reference to unused data
        return endOfData();
      }
    };
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

          if (!duplicate) {
            lastValue = next;
            return lastValue;
          }
        }

        lastValue = null; // clear reference to unused data
        return endOfData();
      }
    };
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

            String next = lines.next();
            // skip last line if it's empty
            if (lines.hasNext() || !next.isEmpty()) {
              return next;
            }
          }
          return endOfData();
        }
      };
    }

    @Override
    // If users use this when they shouldn't, we hope that NewApi will catch subsequent Stream calls
    @IgnoreJRERequirement

            String next = lines.next();
            // skip last line if it's empty
            if (lines.hasNext() || !next.isEmpty()) {
              return next;
            }
          }
          return endOfData();
        }
      };
    }

    @Override
    public Stream<String> lines() {
      return stream(linesIterator());
    }

    @Override
    public @Nullable String readFirstLine() {

        while (unfiltered.hasNext()) {
          T element = unfiltered.next();
          if (retainIfTrue.apply(element)) {
            return element;
          }
        }
        return endOfData();
      }
    };
  }

  /**
   * Returns a view of {@code unfiltered} containing all elements that are of the type {@code
   * desiredType}.
   */