code: @NotNull
      public Stream<IntPair<T>> indexed(final int from, final int step) {
          return mapIndexed(from, step, new IndexedFunction<T, IntPair<T>>() {
  
              @NotNull
              @Override
              public IntPair<T> apply(int index, T t) {
                  return new IntPair<T>(index, t);
              }
          });
      }
docs: Returns {@code Stream} with indexed elements.
  
  <p>This is an intermediate operation.
  
  <p>Example:
  <pre>
  from: 5, step: 10
  stream: ["a", "b", "c"]
  result: [(5, "a"), (15, "b"), (25, "c")]
  </pre>
  
  @param from  the initial value (inclusive)
  @param step  the step
  @return the new {@code IntPair} stream
  @since 1.1.2