@Override
	public boolean applyTo(Program program) {
		Listing listing = program.getListing();
		ProgramModule m = listing.getModule(treeName, parentName);
		if (m == null) {
			statusMsg = "Module named " + parentName + " does not exist";
			return false;
		}

		try {
			m.createFragment(name);
			return true;
		}
		catch (DuplicateNameException e) {
			statusMsg = name + " already exists";
		}
		return false;
	}
Apply the command; if the name already exists, then the fragment 
will not be created.
@return false if the fragment was not created
@see ghidra.framework.cmd.Command#applyTo(ghidra.framework.model.DomainObject)
Ghidra/Features/Base/src/main/java/ghidra/app/cmd/module/CreateFragmentCmd.java