$neighbors = {
   a => { 
     q => 1,
     w => 1,
     s => 1,
     z => 1,
   },
   s => {
     a => 1,
     w => 1,
     e => 1,
     d => 1,
     x => 1,
     z => 1,
   },
 
   etc.
}