我创建了一个名为Sudoku的类，将数独存储在类实例中。我在这里主要是：
from multiprocessing import Pool
class Sudoku:
...
def resi(self):
... solves the board
if __name__ == "__main__":
def solve(t):
t.resi()
return t
l = ... - a list of unsolved sudoku boards
p = Pool()
l = p.map(solve, l)
我收到此错误：
File "/usr/lib/python3.5/runpy.py", line 184, in _run_module_as_main
"__main__", mod_spec)
File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/usr/lib/python3.5/cProfile.py", line 160, in <module>
main()
File "/usr/lib/python3.5/cProfile.py", line 153, in main
runctx(code, globs, None, options.outfile, options.sort)
File "/usr/lib/python3.5/cProfile.py", line 20, in runctx
filename, sort)
File "/usr/lib/python3.5/profile.py", line 64, in runctx
prof.runctx(statement, globals, locals)
File "/usr/lib/python3.5/cProfile.py", line 100, in runctx
exec(cmd, globals, locals)
File "sudoku.py", line 94, in <module>
lista = p.map(solve, lista)
File "/usr/lib/python3.5/multiprocessing/pool.py", line 260, in map
return self._map_async(func, iterable, mapstar, chunksize).get()
File "/usr/lib/python3.5/multiprocessing/pool.py", line 608, in get
raise self._value
File "/usr/lib/python3.5/multiprocessing/pool.py", line 385, in _handle_tasks
put(task)
File "/usr/lib/python3.5/multiprocessing/connection.py", line 206, in send
self._send_bytes(ForkingPickler.dumps(obj))
File "/usr/lib/python3.5/multiprocessing/reduction.py", line 50, in dumps
cls(buf, protocol).dump(obj)
_pickle.PicklingError: Can't pickle <function solve at 0x7f55e09d7158>: attribute lookup solve on __main__ failed
我做错了什么？