private Value regValue(SymbolicPropogator symEval, Address addr, String regName) {
		ProgramContext context = program.getProgramContext();
		Register reg = context.getRegister(regName);
		return symEval.getRegisterValue(addr, reg);
	}
quick and dirty test of the ProgramContextImpl just to see
if the values are being set for specified address range.
The ProgramContextPlugin will be a more complete test
program, with a gui interface to specify the values and
select/highlight an address range.
Ghidra/Features/Base/src/test/java/ghidra/program/util/ConstantPropogationReferenceTest.java