(plaintiff, defendant’s farm employee, lost leg when filling storage bin with soybeans; defendant had cut hole in auger hopper to assist with auger’s repair; hole covered with soybeans and not visible to plaintiff who knew of hole and stepped into hole during filling process; plaintiff sued for negligence and trial court granted summary judgment for defendant because hole open and obvious; appellate court reversed on basis that evidence sufficient that plaintiff, while know of hole, couldn’t see it).