

class     lowercase_       :



      def __init__(     self :							Tuple     ,   A__ :							Tuple						)       ->	Optional[int]:
        _snake_case		=				data
        _snake_case		=				None
        _snake_case		=				None







      def __str__(     self :							Union[str, Any]						)       ->	Optional[int]:
        return f"""{self.data}"""



class     lowercase_       :



      def __init__(     self :							Any						)       ->	List[str]:
        _snake_case		=				None
        _snake_case		=				None



      def __iter__(     self :							Dict						)       ->	List[Any]:
        _snake_case		=				self.head
        while node:
          yield node.data
          _snake_case		=				node.next



      def __str__(     self :							Dict						)       ->	Union[str, Any]:
        return "->".join([str(__SCREAMING_SNAKE_CASE						) for item in self]						)



      def __len__(     self :							List[Any]						)       ->	Any:
        return sum(1 for _ in self						)



      def 		UpperCamelCase_						(     self :							Any     ,   A__ :							int						)       ->	List[Any]:
        self.insert_at_nth(0     ,   __SCREAMING_SNAKE_CASE						)



      def 		UpperCamelCase_						(     self :							Optional[Any]     ,   A__ :							Tuple						)       ->	Optional[int]:
        self.insert_at_nth(len(self						)     ,   __SCREAMING_SNAKE_CASE						)



      def 		UpperCamelCase_						(     self :							Dict     ,   A__ :							Tuple     ,   A__ :							List[str]						)       ->	List[str]:
        _snake_case		=				len(self						)

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



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



      def 		UpperCamelCase_						(     self :							str						)       ->	str:
        return self.delete_at_nth(len(self						) - 1						)



      def 		UpperCamelCase_						(     self :							Optional[Any]     ,   A__ :							Optional[int]						)       ->	Union[str, Any]:
        _snake_case		=				len(self						)

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



      def 		UpperCamelCase_						(     self :							Union[str, Any]     ,   A__ :							str						)       ->	str:
        _snake_case		=				self.head

        while current.data != data:  # Find the position to delete
          if current.next:
            _snake_case		=				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
          _snake_case		=				current.next  # 1 --> 3
          _snake_case		=				current.previous  # 1 <--> 3
        return data







      def 		UpperCamelCase_						(     self :							Union[str, Any]						)       ->	Dict:
        return len(self						) == 0



def  snake_case_()				->      None:



  """simple docstring"""






  _snake_case		=				DoublyLinkedList()
  assert linked_list.is_empty() is True
  assert str(A_	) == ""

  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(10	):
    assert len(A_	) == i
    linked_list.insert_at_nth(A_					,			i + 1	)
  assert str(A_	) == "->".join(str(A_	) for i in range(1					,			11	)	)

  linked_list.insert_at_head(0	)
  linked_list.insert_at_tail(11	)
  assert str(A_	) == "->".join(str(A_	) for i in range(0					,			12	)	)

  assert linked_list.delete_head() == 0
  assert linked_list.delete_at_nth(9	) == 10
  assert linked_list.delete_tail() == 11
  assert len(A_	) == 9
  assert str(A_	) == "->".join(str(A_	) for i in range(1					,			10	)	)


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

 testmod()





def 	_lowerCamelCase  (		A_  :	float							,  A_  :	float							,  A_  :	int      )			->			float:

   '''simple docstring'''






   UpperCamelCase__ :			Union[str, Any] 						=[1 / first_term]
   UpperCamelCase__ :			Tuple 						=1 / first_term
   for _ in range(number_of_terms - 1      ):
      first_term += common_difference
      arithmetic_progression.append(A_      )
   UpperCamelCase__ :			List[str] 						=[1 / step for step in arithmetic_progression]
   return sum(A_      )


if __name__ == "__main__":
     import doctest

     doctest.testmod()
     print(sum_of_harmonic_progression(1 / 2, 2, 2))

