addAround method
Returns new list with items generated around list
final list = ['π','π','π'];
final newList = addAround(list, (index,previous,next) => 'π¨');
print(newList);//['π¨','π','π¨','π','π¨','π','π¨']
Implementation
List<V> addAround(fn.Generator<V> generate) => fn.addAround(this, generate);