code: def find_collisions( self, checked_ops ):
          
  
          collisions = {}
          for op in checked_ops:
              if BlockstackDB.nameop_is_collided( op ):
                  BlockstackDB.nameop_put_collision( collisions, op )
  
          return collisions
docs: Given a list of checked operations, find the ones that collide.
          Return a dict structured as history_id_key --> [history_id]