protected void encodeHeader(Encoder encoder) throws IOException {
		encoder.writeSignedInteger(ATTRIB_INDEX, index);
	}
Encode basic attributes to stream. Assume this block's element is already started.
@param encoder is the stream encoder
@throws IOException for errors writing to the underlying stream
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/PcodeBlock.java