





class 		_lowerCAmelCase:

  """simple docstring"""







  def __init__(   self    ,							UpperCAmelCase      )->   int:
     __A    =  data
     __A    =  None
     __A    =  None





  def __str__(   self      )->   List[str]:
     return f"{self.data}"







class 		_lowerCAmelCase:

  """simple docstring"""







  def __init__(   self      )->   int:
     __A    =  None
     __A    =  None

  def __iter__(   self      )->   Optional[Any]:
     __A    =  self.head
     while node:
        yield node.data
        __A    =  node.next

  def __str__(   self      )->   List[Any]:
     return "->".join([str(A_      ) for item in self]      )

  def __len__(   self      )->   int:
     return sum(1 for _ in self      )

  def 						SCREAMING_SNAKE_CASE__			(   self    ,							UpperCAmelCase      )->   Tuple:
     self.insert_at_nth(0    ,							A_      )

  def 						SCREAMING_SNAKE_CASE__			(   self    ,							UpperCAmelCase      )->   List[str]:
     self.insert_at_nth(len(self      )    ,							A_      )

  def 						SCREAMING_SNAKE_CASE__			(   self    ,							UpperCAmelCase    ,							UpperCAmelCase      )->   List[str]:
     __A    =  len(self      )

     if not 0 <= index <= length:
        raise IndexError('''list index out of range'''      )
     __A    =  Node(A_      )
     if self.head is None:
        __A    =  __A    =  new_node
     elif index == 0:
        __A    =  new_node
        __A    =  self.head
        __A    =  new_node
     elif index == length:
        __A    =  new_node
        __A    =  self.tail
        __A    =  new_node
     else:
        __A    =  self.head
        for _ in range(0    ,							A_      ):
           __A    =  temp.next
        __A    =  new_node
        __A    =  temp.previous
        __A    =  temp
        __A    =  new_node

  def 						SCREAMING_SNAKE_CASE__			(   self      )->   List[str]:
     return self.delete_at_nth(0      )

  def 						SCREAMING_SNAKE_CASE__			(   self      )->   int:
     return self.delete_at_nth(len(self      ) - 1      )

  def 						SCREAMING_SNAKE_CASE__			(   self    ,							UpperCAmelCase      )->   Optional[Any]:
     __A    =  len(self      )

     if not 0 <= index <= length - 1:
        raise IndexError('''list index out of range'''      )
     __A    =  self.head  # default first node
     if length == 1:
        __A    =  __A    =  None
     elif index == 0:
        __A    =  self.head.next
        __A    =  None
     elif index == length - 1:
        __A    =  self.tail
        __A    =  self.tail.previous
        __A    =  None
     else:
        __A    =  self.head
        for _ in range(0    ,							A_      ):
           __A    =  temp.next
        __A    =  temp
        __A    =  temp.previous
        __A    =  temp.next
     return delete_node.data

  def 						SCREAMING_SNAKE_CASE__			(   self    ,							UpperCAmelCase      )->   str:
     __A    =  self.head

     while current.data != data:  # Find the position to delete
        if current.next:
           __A    =  current.next
        else:  # We have reached the end an no value matches
           raise ValueError('''No data matching given value'''      )

     if current == self.head:
        self.delete_head()

     elif current == self.tail:
        self.delete_tail()

     else:  # Before: 1 <--> 2(current) <--> 3
        __A    =  current.next  # 1 --> 3
        __A    =  current.previous  # 1 <--> 3
     return data





  def 						SCREAMING_SNAKE_CASE__			(   self      )->   List[Any]:
     return len(self      ) == 0
def  __UpperCamelCase    (						)    ->		None:


   '''simple docstring'''







   __A    =  DoublyLinkedList()
   assert linked_list.is_empty() is True
   assert str(__UpperCAmelCase      ) == ""

   try:
      linked_list.delete_head()
      raise AssertionError  # This should not happen.
   except IndexError:
      assert True  # This should happen.

   try:
      linked_list.delete_tail()
      raise AssertionError  # This should not happen.
   except IndexError:
      assert True  # This should happen.

   for i in range(1_0      ):
      assert len(__UpperCAmelCase      ) == i
      linked_list.insert_at_nth(__UpperCAmelCase							,			i + 1      )
   assert str(__UpperCAmelCase      ) == "->".join(str(__UpperCAmelCase      ) for i in range(1							,			1_1      )      )

   linked_list.insert_at_head(0      )
   linked_list.insert_at_tail(1_1      )
   assert str(__UpperCAmelCase      ) == "->".join(str(__UpperCAmelCase      ) for i in range(0							,			1_2      )      )

   assert linked_list.delete_head() == 0
   assert linked_list.delete_at_nth(9      ) == 1_0
   assert linked_list.delete_tail() == 1_1
   assert len(__UpperCAmelCase      ) == 9
   assert str(__UpperCAmelCase      ) == "->".join(str(__UpperCAmelCase      ) for i in range(1							,			1_0      )      )


if __name__ == "__main__":
    from doctest import testmod

    testmod()


import torch

from accelerate import Accelerator, DistributedType



class 			UpperCamelCase					:

     '''simple docstring'''

     def __enter__(       self    )			->					int:






           """simple docstring"""
           if self.enabled:
                 _lowerCamelCase           =					self.model.no_sync()
                 self.model_sync_obj.__enter__()

           return self



     def __exit__(       self					,					A_					,					A_					,					A_    )			->					Union[str, Any]:






           """simple docstring"""
           if self.enabled:
                 # Average all models on exit
                 self._sync_and_avg_model_params()
                 self.model_sync_obj.__exit__(A_					,					A_					,					A_    )



     def __init__(       self					,					A_					,					A_					,					A_					,					A_ = True    )			->					List[str]:






           """simple docstring"""
           if accelerator.distributed_type not in [
               DistributedType.NO,
               DistributedType.MULTI_CPU,
               DistributedType.MULTI_GPU,
           ]:
                 raise NotImplementedError('''LocalSGD is supported only for CPUs and GPUs (no DeepSpeed or MegatronLM)'''    )
           _lowerCamelCase           =					enabled and accelerator.distributed_type != DistributedType.NO
           _lowerCamelCase           =					0
           if self.enabled:
                 _lowerCamelCase           =					accelerator
                 _lowerCamelCase           =					model
                 _lowerCamelCase           =					local_sgd_steps



     def 		UpperCamelCase_    (       self    )			->					Optional[Any]:






           """simple docstring"""
           self.num_steps += 1
           if not self.enabled:
                 return

           if self.num_steps % self.local_sgd_steps == 0:
                 self._sync_and_avg_model_params()





     def 		UpperCamelCase_    (       self    )			->					Union[str, Any]:






           """simple docstring"""
           self.accelerator.wait_for_everyone()
           with self.accelerator.autocast():
                 for param in self.model.parameters():
                       _lowerCamelCase           =					self.accelerator.reduce(param.data					,					reduction='''mean'''    )