▁argument , ▁it ▁returns ▁the ▁value ▁of ▁the ▁given ▁variable ▁( it ▁must ▁exist ▁in ▁this ▁case ). ▁ ▁proc ▁defines ▁a ▁new ▁command , ▁whose ▁execution ▁results ▁in ▁executing ▁a ▁given ▁T cl ▁script , ▁written ▁as ▁a ▁set ▁of ▁commands . ▁return ▁can ▁be ▁used ▁to ▁immediately ▁return ▁control ▁to ▁the ▁caller . ▁ ▁The ▁usual ▁execution ▁control ▁commands ▁are : ▁ ▁if ▁executes ▁given ▁script ▁body ▁( second ▁argument ), ▁if ▁the ▁condition ▁( first ▁argument ) ▁is ▁satisfied . ▁It ▁can ▁be ▁followed ▁by ▁additional ▁arguments ▁starting ▁from ▁else if ▁with ▁the ▁alternative ▁condition ▁and ▁body , ▁or ▁else ▁with ▁the ▁complement ary ▁block . ▁ ▁while ▁repe ats ▁executing ▁given ▁script ▁body , ▁as ▁long ▁as ▁the ▁condition ▁( first ▁argument ) ▁remains ▁satisfied ▁ ▁foreach ▁executes ▁given ▁body ▁where ▁the ▁control ▁variable ▁is ▁assigned ▁list ▁elements ▁one ▁by ▁one . ▁ ▁for ▁shortcut ▁for ▁initial izing ▁the ▁control ▁variable , ▁condition ▁( as ▁in ▁while ) ▁and ▁the ▁additional ▁" next ▁iteration " ▁statement ▁( command ▁executed ▁after ▁executing ▁the ▁body ) ▁ ▁Those ▁above ▁looping ▁commands ▁can ▁be ▁addition ally ▁controlled ▁by ▁the ▁following ▁commands : ▁ ▁break ▁interrupt s ▁the ▁body ▁execution ▁and ▁returns ▁from ▁the ▁looping ▁command ▁ ▁continue ▁interrupt s ▁the ▁body ▁execution , ▁but ▁the ▁control ▁is ▁still ▁given ▁back ▁to ▁the ▁looping ▁command . ▁For ▁while ▁it ▁means ▁to ▁loop ▁again , ▁for ▁for ▁and ▁foreach , ▁pick ▁up ▁the ▁next ▁iteration . ▁ ▁return ▁interrupt s ▁the ▁execution ▁of ▁the