code: ByteVector put12(final int b, final int s) {
          int length = this.length;
          if (length + 3 > data.length) {
              enlarge(3);
          }
          byte[] data = this.data;
          data[length++] = (byte) b;
          data[length++] = (byte) (s >>> 8);
          data[length++] = (byte) s;
          this.length = length;
          return this;
      }
docs: Puts a byte and a short into this byte vector. The byte vector is
  automatically enlarged if necessary.
  
  @param b
  a byte.
  @param s
  a short.
  @return this byte vector.