code: 
  
  
  
  
  
  
  import safs
  
  
  
  
  
  class     __a						(					safs.SaFileSystem ):
   pass
style_context: 
  
  
  
  
  
  
  from __future__ import annotations
  
  from collections.abc import Iterator
  from typing import Any
  
  
  
  
  
  class     __a						:
  
  
  
  
  
  
  
   def __init__(	self      :     str							,     SCREAMING_SNAKE_CASE      :     Any		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        UpperCamelCase__    :     Any        =						data
        UpperCamelCase__    :     Node | None        =						None
  
  
  
  
  
  
  
   def __str__(	self      :     Union[str, Any]		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        return F'{self.data}'
  
  
  
  
  
  
  
  class     __a						:
  
  
  
  
  
  
  
   def __init__(	self      :     Optional[int]		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        UpperCamelCase__    :     Node | None        =						None
        UpperCamelCase__    :     Node | None        =						None
  
  
  
  
  
  
  
   def __iter__(	self      :     str		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        UpperCamelCase__    :     int        =						self.front
        while node:
             yield node.data
             UpperCamelCase__    :     Any        =						node.next
  
  
  
  
  
  
  
   def __len__(	self      :     Tuple		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        return len(tuple(iter(self		)		)		)
  
  
  
  
  
  
  
   def __str__(	self      :     Union[str, Any]		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        return " <- ".join(str(SCREAMING_SNAKE_CASE		) for item in self		)
  
  
  
  
  
  
  
   def       __lowercase      (	self      :     List[str]		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        return len(self		) == 0
  
  
  
  
  
  
  
   def       __lowercase      (	self      :     Union[str, Any]							,     SCREAMING_SNAKE_CASE      :     Any		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        UpperCamelCase__    :     int        =						Node(SCREAMING_SNAKE_CASE		)
        if self.is_empty():
             UpperCamelCase__    :     int        =						node
        else:
             assert isinstance(self.rear							,     SCREAMING_SNAKE_CASE		)
             UpperCamelCase__    :     Dict        =						node
             UpperCamelCase__    :     str        =						node
  
  
  
  
  
  
  
   def       __lowercase      (	self      :     Dict		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        if self.is_empty():
             raise IndexError("dequeue from empty queue"		)
        assert isinstance(self.front							,     SCREAMING_SNAKE_CASE		)
        UpperCamelCase__    :     Optional[int]        =						self.front
        UpperCamelCase__    :     List[str]        =						self.front.next
        if self.front is None:
             UpperCamelCase__    :     List[Any]        =						None
        return node.data
  
  
  
  
  
  
  
   def       __lowercase      (	self      :     str		):
  
  
        '''simple docstring'''
  
  
  
  
  
  
        UpperCamelCase__    :     Optional[int]        =						None
  
  
  if __name__ == "__main__":
   from doctest import testmod
  
   testmod()