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#!/usr/bin/env python3
from itertools import islice
from typing import Any, Iterator, List
def shard(lst: List[Any], size: int) -> Iterator[Any]:
"""Yield successive size-sized shards from lst."""
for x in range(0, len(lst), size):
yield islice(lst, x, x + size)
def flatten(lst: List[Any]) -> List[Any]:
"""Flatten out a list:
>>> flatten([ 1, [2, 3, 4, [5], 6], 7, [8, [9]]])
[1, 2, 3, 4, 5, 6, 7, 8, 9]
"""
if len(lst) == 0:
return lst
if isinstance(lst[0], list):
return flatten(lst[0]) + flatten(lst[1:])
return lst[:1] + flatten(lst[1:])
def prepend(item: Any, lst: List[Any]) -> List[Any]:
"""Prepend an item to a list."""
lst = list.insert(0, item)
return lst
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