code: @NotNull
      public LongStream sample(final int stepWidth) {
          if (stepWidth <= 0) throw new IllegalArgumentException("stepWidth cannot be zero or negative");
          if (stepWidth == 1) return this;
          return new LongStream(params, new LongSample(iterator, stepWidth));
      }
docs: Samples the {@code LongStream} by emitting every n-th element.
  
  <p>This is an intermediate operation.
  
  <p>Example:
  <pre>
  stepWidth: 3
  stream: [1, 2, 3, 4, 5, 6, 7, 8]
  result: [1, 4, 7]
  </pre>
  
  @param stepWidth  step width
  @return the new {@code LongStream}
  @throws IllegalArgumentException if {@code stepWidth} is zero or negative
  @see Stream#sample(int)