Stepwise refinement open walk to door reach for knob open door;- repeat until door opens turn knob clockwise walk through; if knob doesn't turn, then close door take key out find correct key insert in lock endif pull/push door move out of way end repeatStepwise Refinement open walk to door; reach for knob; open door; walk through; close door. repeat until door opens turn knob clockwise; if knob doesn't turn, then take key out; find correct key; insert in lock; endif pull/push door move out of way; end repeat