const isValidWalk = (walk) => {
  let coords = [0, 0];
  let time = 0;
  walk.forEach(dir => {
  switch (dir) {
      case 'n':
        coords[0]++;
        time++;
        break;
      case 's':
        coords[0]--;
        time++;
        break;
      case 'e':
        coords[1]++;
        time++;
        break;
      case 'w':
        coords[1]--;
        time++;
        break;
    }
  });
  
  if (time == 10) {
    if (coords[0] == 0 && coords[1] == 0) {
      return true;
    }
  }
  
  return false;
}