code: func (f *fieldVal) SetByteSlice(b []byte) *fieldVal {
  	var b32 [32]byte
  	for i := 0; i < len(b); i++ {
  		if i < 32 {
  			b32[i+(32-len(b))] = b[i]
  		}
  	}
  	return f.SetBytes(&b32)
  }
docs: // SetByteSlice packs the passed big-endian value into the internal field value
  // representation.  Only the first 32-bytes are used.  As a result, it is up to
  // the caller to ensure numbers of the appropriate size are used or the value
  // will be truncated.
  //
  // The field value is returned to support chaining.  This enables syntax like:
  // f := new(fieldVal).SetByteSlice(byteSlice)