public void setItemChecked(long position, boolean checked) {
        helper.setItemChecked(position, checked);
    }
Changes the selection of an item. If the item was already in the specified state, nothing is done. May cause the
activation of the action mode if an item is selected an no items were previously selected

@param position
           The position of the item to select
@param checked
           The desired state (selected or not) for the item
extras/actionbarcompat/src/com/manuelpeinado/multichoiceadapter/extras/actionbarcompat/MultiChoiceBaseAdapter.java