code: public static DoubleStreamEx of(java.nio.DoubleBuffer buf) {
          return IntStreamEx.range(buf.position(), buf.limit()).mapToDouble(buf::get);
      }
docs: Returns a sequential ordered {@code DoubleStreamEx} whose elements are
  the values in the supplied {@link java.nio.DoubleBuffer}.
  
  <p>
  The resulting stream covers only a portion of {@code DoubleBuffer}
  content which starts with {@linkplain Buffer#position() position}
  (inclusive) and ends with {@linkplain Buffer#limit() limit} (exclusive).
  Changes in position and limit after the stream creation don't affect the
  stream.
  
  <p>
  The resulting stream does not change the internal {@code DoubleBuffer}
  state.
  
  @param buf the {@code DoubleBuffer} to create a stream from
  @return the new stream
  @since 0.6.2