
'''simple docstring'''
from typing import TYPE_CHECKING

from ...utils import (
    OptionalDependencyNotAvailable,
    _LazyModule,
    is_flax_available,
    is_sentencepiece_available,
    is_tf_available,
    is_tokenizers_available,
    is_torch_available,
)


a_      =  {"configuration_pegasus": ["PEGASUS_PRETRAINED_CONFIG_ARCHIVE_MAP", "PegasusConfig"]}

try:
  if not is_sentencepiece_available():
    raise OptionalDependencyNotAvailable()
except OptionalDependencyNotAvailable:
  pass
else:
  a_      =  ["PegasusTokenizer"]

try:
  if not is_tokenizers_available():
    raise OptionalDependencyNotAvailable()
except OptionalDependencyNotAvailable:
  pass
else:
  a_      =  ["PegasusTokenizerFast"]

try:
  if not is_torch_available():
    raise OptionalDependencyNotAvailable()
except OptionalDependencyNotAvailable:
  pass
else:
  a_      =  [
      "PEGASUS_PRETRAINED_MODEL_ARCHIVE_LIST",
      "PegasusForCausalLM",
      "PegasusForConditionalGeneration",
      "PegasusModel",
      "PegasusPreTrainedModel",
  ]

try:
  if not is_tf_available():
    raise OptionalDependencyNotAvailable()
except OptionalDependencyNotAvailable:
  pass
else:
  a_      =  [
      "TFPegasusForConditionalGeneration",
      "TFPegasusModel",
      "TFPegasusPreTrainedModel",
  ]

try:
  if not is_flax_available():
    raise OptionalDependencyNotAvailable()
except OptionalDependencyNotAvailable:
  pass
else:
  a_      =  [
      "FlaxPegasusForConditionalGeneration",
      "FlaxPegasusModel",
      "FlaxPegasusPreTrainedModel",
  ]


if TYPE_CHECKING:
  from .configuration_pegasus import PEGASUS_PRETRAINED_CONFIG_ARCHIVE_MAP, PegasusConfig

  try:
    if not is_sentencepiece_available():
      raise OptionalDependencyNotAvailable()
  except OptionalDependencyNotAvailable:
    pass
  else:
    from .tokenization_pegasus import PegasusTokenizer

  try:
    if not is_tokenizers_available():
      raise OptionalDependencyNotAvailable()
  except OptionalDependencyNotAvailable:
    pass
  else:
    from .tokenization_pegasus_fast import PegasusTokenizerFast

  try:
    if not is_torch_available():
      raise OptionalDependencyNotAvailable()
  except OptionalDependencyNotAvailable:
    pass
  else:
    from .modeling_pegasus import (
        PEGASUS_PRETRAINED_MODEL_ARCHIVE_LIST,
        PegasusForCausalLM,
        PegasusForConditionalGeneration,
        PegasusModel,
        PegasusPreTrainedModel,
    )

  try:
    if not is_tf_available():
      raise OptionalDependencyNotAvailable()
  except OptionalDependencyNotAvailable:
    pass
  else:
    from .modeling_tf_pegasus import TFPegasusForConditionalGeneration, TFPegasusModel, TFPegasusPreTrainedModel

  try:
    if not is_flax_available():
      raise OptionalDependencyNotAvailable()
  except OptionalDependencyNotAvailable:
    pass
  else:
    from .modeling_flax_pegasus import (
        FlaxPegasusForConditionalGeneration,
        FlaxPegasusModel,
        FlaxPegasusPreTrainedModel,
    )

else:
  import sys

  a_      =  _LazyModule(__name__, globals()["__file__"], _import_structure, module_spec=__spec__)










from __future__ import annotations

from typing import Generic, TypeVar

lowerCamelCase_  						=   TypeVar("T")
class       __a					( Generic[T]     ):


     """simple docstring"""


     def __init__(	self			: int				,_UpperCamelCase			: T						)		->   str:


         '''simple docstring'''





         SCREAMING_SNAKE_CASE__								=data  # Assign data
         SCREAMING_SNAKE_CASE__								=None  # Initialize next as null
         SCREAMING_SNAKE_CASE__								=None  # Initialize prev as null






class       __a					( Generic[T]     ):


     """simple docstring"""


     def __init__(	self			: Tuple						)		->   None:


         '''simple docstring'''





         SCREAMING_SNAKE_CASE__								=None




     def   __A				(	self			: Dict				,_UpperCamelCase			: T						)		->   None:


         '''simple docstring'''





         if self.head is None:
             SCREAMING_SNAKE_CASE__								=Node(_UpperCamelCase						)
         else:
             SCREAMING_SNAKE_CASE__								=Node(_UpperCamelCase						)
             SCREAMING_SNAKE_CASE__								=new_node
             SCREAMING_SNAKE_CASE__								=self.head
             SCREAMING_SNAKE_CASE__								=None
             SCREAMING_SNAKE_CASE__								=new_node




     def   __A				(	self			: List[str]						)		->   T | None:


         '''simple docstring'''





         if self.head is None:
             return None
         else:
             assert self.head is not None
             SCREAMING_SNAKE_CASE__								=self.head.data
             SCREAMING_SNAKE_CASE__								=self.head.next
             if self.head is not None:
                 SCREAMING_SNAKE_CASE__								=None
             return temp




     def   __A				(	self			: List[str]						)		->   T | None:


         '''simple docstring'''





         return self.head.data if self.head is not None else None




     def __len__(	self			: Optional[int]						)		->   int:


         '''simple docstring'''





         SCREAMING_SNAKE_CASE__								=self.head
         SCREAMING_SNAKE_CASE__								=0
         while temp is not None:
             count += 1
             SCREAMING_SNAKE_CASE__								=temp.next
         return count




     def   __A				(	self			: List[Any]						)		->   bool:


         '''simple docstring'''





         return self.head is None




     def   __A				(	self			: int						)		->   None:


         '''simple docstring'''





         print("""stack elements are:"""						)
         SCREAMING_SNAKE_CASE__								=self.head
         while temp is not None:
             print(temp.data				,end="""->"""						)
             SCREAMING_SNAKE_CASE__								=temp.next


# Code execution starts here
if __name__ == "__main__":
    # Start with the empty stack
    lowerCamelCase_  						=   Stack()

    # Insert 4 at the beginning. So stack becomes 4->None
    print("Stack operations using Doubly LinkedList")
    stack.push(4)

    # Insert 5 at the beginning. So stack becomes 4->5->None
    stack.push(5)

    # Insert 6 at the beginning. So stack becomes 4->5->6->None
    stack.push(6)

    # Insert 7 at the beginning. So stack becomes 4->5->6->7->None
    stack.push(7)

    # Print the stack
    stack.print_stack()

    # Print the top element
    print("\nTop element is ", stack.top())

    # Print the stack size
    print("Size of the stack is ", len(stack))

    # pop the top element
    stack.pop()

    # pop the top element
    stack.pop()

    # two elements have now been popped off
    stack.print_stack()

    # Print True if the stack is empty else False
    print("\nstack is empty:", stack.is_empty())






