@@ -0,0 +1,433 @@
+package seedu.oneline.logic.commands;%0A%0Apublic abstract class MutatingCommand extends Command %7B%0A    protected CommandAction undoAction = null;%0A    private int stateWhenDone = -1;%0A    %0A    protected static abstract class CommandAction %7B%0A        public abstract void execute() throws Exception;%0A    %7D%0A    %0A    public void undo() %7B%0A        // Todo%0A    %7D%0A%0A    @Override%0A    public boolean isMutating() %7B%0A        return true;%0A    %7D%0A    %0A%7D%0A

Add MutatingCommand class