private boolean pushInstruction(Stack<CodeUnit> cuStack, Address addr) {
		if (addr == null) {
			return false;
		}
		CodeUnit codeUnit = program.getListing().getInstructionAt(addr);
		if (codeUnit != null) {
			cuStack.push(codeUnit);
			return true;
		}
		return false;
	}
Push the instruction at the indicated address onto the flow stack. If the
indicated address is not the min address of a code unit then do nothing.
@param cuStack the code unit stack of flows to be followed
@param addr the address of the code unit
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/block/FollowFlow.java