divide list ['a', 'b', 'c', '1', '2', '3'] evenly into three separate list

def divide_list(a_list):
  return [a_list[:len(a_list)/3], a_list[len(a_list)/3:(len(a_list)/3)*2], a_list[(len(a_list)/3)*2:]] 
    
divide_list(['a', 'b', 'c', '1', '2', '3'])