public void checkPoint(Program program) {
		Integer id = openPrograms.get(program);
		if (id == null || id.intValue() < 0) {
			throw new IllegalStateException("Cannot checkpoint a read-only program");
		}
		program.endTransaction(id.intValue(), true);
		openPrograms.put(program, Integer.valueOf(program.startTransaction("")));
	}
Creates a checkpoint in the program. Any changes since the last
checkpoint can be instantly undone by calling the rollback command.

@param program
           the program to be checkpointed.
Ghidra/Features/Base/src/main/java/ghidra/base/project/GhidraProject.java