int getProgramIndex(Program pgm) {
		if (pgm == programs[RESULT]) {
			return RESULT;
		}
		else if (pgm == programs[LATEST]) {
			return LATEST;
		}
		else if (pgm == programs[MY]) {
			return MY;
		}
		else if (pgm == programs[ORIGINAL]) {
			return ORIGINAL;
		}
		return -1;
	}
Gets the merge constant associated with the indicated program.
@param pgm the program
@return RESULT, LATEST, MY, ORIGINAL, or -1.
A value of -1 indicates the program is not one of the four versioned programs.
@see MergeConstants
Ghidra/Features/Base/src/main/java/ghidra/app/merge/listing/FunctionMerger.java