text: from .vector import Vec4
  from .matrix import Mat4
  from .s_cons import s_dict
  import pickle
  
  RCON = []
  for c in ['01', '02', '04', '08', '10', '20', '40', '80', '1b', '36']:
      RCON.append(
          Vec4('{} 00 00 00'.format(c))
      )
  
  def extend_key(k):
      key_word_list = list(k.c_list)
      for i in range(10):
          for j in range(4):
              col1 = key_word_list[-1]
              col2 = key_word_list[-4]
              if j==0:
                  col1 = col1.rot_word()
                  col1 = col1.substitute(s_dict)
                  col3 = RCON[i]
                  new_col = col1 + col2 + col3
              else:
                  new_col = col1 + col2
              key_word_list.append(new_col)
      keys = []
      for i in range(11):
          key_chunk = Mat4.from_col_list(list(key_word_list[4*i:4*(i+1)]))
          keys.append(key_chunk)
      return keys