check item list valid remov item call automat valid check thread call user press button forc valid check em warn fragil code em method method call design deadlock param remov list contain item remov deprec bob tarl list design extend requir method us scope futur deprec forc valid check list item remov item item item item valid valid item valid design invalid element except ex element delet longer valid valid except ex valid buffer buf buffer except rais list clean buf append buf append item defin log lp log granular type statement lp log local nest statement lp log local nest ifdef cognit log error buf ex endif valid num valid remov add item item item remov remov item histori histori add item resolut item longer valid item item resolv longer valid notifi observ remov element item recomput offend recomput poster item remov remov 