def bucket_fill_for_trie(node: key.Key, eligible: trie.Trie):
fill = []
finger = eligible
for depth in range(node.bit_len()):
dir = node.bit_at(depth)
if finger.is_leaf():
break
else:
fill.append(finger.branch[1 - dir].size())
finger = finger.branch[dir]
return fill
