divide this ['a', 'b', 'c', '1', '2', '3','4', '5', '6'] evenly into three separate list into one single list

def list_splitting(list_of_items):
  list_of_list = []
  for x in range(0, len(list_of_items), 3):
    single_list = list_of_items[x:x+3]
    list_of_list.append(single_list)
      
  return list_of_list
    
list_splitting(['a', 'b', 'c', '1', '2', '3', '4', '5', '6'])