code: func (f *fieldVal) SetHex(hexString string) *fieldVal {
  	if len(hexString)%2 != 0 {
  		hexString = "0" + hexString
  	}
  	bytes, _ := hex.DecodeString(hexString)
  	return f.SetByteSlice(bytes)
  }
docs: // SetHex decodes the passed big-endian hex string into the internal field value
  // representation.  Only the first 32-bytes are used.
  //
  // The field value is returned to support chaining.  This enables syntax like:
  // f := new(fieldVal).SetHex("0abc").Add(1) so that f = 0x0abc + 1