def only_evens(lst):
""" (list of list of int) -> list of list of int
Return a list of the lists in lst that contain only even integers.
>>> only_evens([[1, 2, 4], [4, 0, 6], [22, 4, 3], [2]])
[[4, 0, 6], [2]]
"""
even_lists = []
for sublist in lst:
even_lists = []
for sublist in lst:
for numb in sublist:
if numb[i]%2 == 0:
even_list.append(sublist)
return even_lists
次のエラーが発生しました: NameError: グローバル名 'i' が定義されていません。関数本体の何が問題になっていますか?