code: public static Binary copy(byte[] bytes, int off, int len) {
          byte[] cpy = new byte[len];
          System.arraycopy(bytes, off, cpy, 0, len);
          return wrap(cpy);
      }
docs: Convenience method to copy a part of a byte array into a byte sequence.
  
  @param bytes Bytes to wrap.
  @param off   Offset in source bytes to start reading from.
  @param len   Number of bytes to copy.
  @return The wrapped byte sequence.