code: func StatesMarshalEqual(a, b *states.State) bool {
  	var aBuf bytes.Buffer
  	var bBuf bytes.Buffer
  
  	// nil states are not valid states, and so they can never martial equal.
  	if a == nil || b == nil {
  		return false
  	}
  
  	// We write here some temporary files that have no header information
  	// populated, thus ensuring that we're only comparing the state itself
  	// and not any metadata.
  	err := Write(&File{State: a}, &aBuf)
  	if err != nil {
  		// Should never happen, because we're writing to an in-memory buffer
  		panic(err)
  	}
  	err = Write(&File{State: b}, &bBuf)
  	if err != nil {
  		// Should never happen, because we're writing to an in-memory buffer
  		panic(err)
  	}
  
  	return bytes.Equal(aBuf.Bytes(), bBuf.Bytes())
  }
docs: // StatesMarshalEqual returns true if and only if the two given states have
  // an identical (byte-for-byte) statefile representation.
  //
  // This function compares only the portions of the state that are persisted
  // in state files, so for example it will not return false if the only
  // differences between the two states are local values or descendent module
  // outputs.