code: def pad_sequence(
      sequence,
      n,
      pad_left=False,
      pad_right=False,
      left_pad_symbol=None,
      right_pad_symbol=None,
  ):
      """
      Returns a padded sequence of items before ngram extraction.
  
          >>> list(pad_sequence([1,2,3,4,5], 2, pad_left=True, pad_right=True, left_pad_symbol='<s>', right_pad_symbol='</s>'))
          ['<s>', 1, 2, 3, 4, 5, '</s>']
          >>> list(pad_sequence([1,2,3,4,5], 2, pad_left=True, left_pad_symbol='<s>'))
          ['<s>', 1, 2, 3, 4, 5]
          >>> list(pad_sequence([1,2,3,4,5], 2, pad_right=True, right_pad_symbol='</s>'))
          [1, 2, 3, 4, 5, '</s>']
  
      :param sequence: the source data to be padded
      :type sequence: sequence or iter
      :param n: the degree of the ngrams
      :type n: int
      :param pad_left: whether the ngrams should be left-padded
      :type pad_left: bool
      :param pad_right: whether the ngrams should be right-padded
      :type pad_right: bool
      :param left_pad_symbol: the symbol to use for left padding (default is None)
      :type left_pad_symbol: any
      :param right_pad_symbol: the symbol to use for right padding (default is None)
      :type right_pad_symbol: any
      :rtype: sequence or iter
      """
      sequence = iter(sequence)
      if pad_left:
          sequence = chain((left_pad_symbol,) * (n - 1), sequence)
      if pad_right:
          sequence = chain(sequence, (right_pad_symbol,) * (n - 1))
      return sequence
  
imports: import inspect
  import locale
  import os
  import pydoc
  import re
  import textwrap
  import unicodedata
  import warnings
  from collections import defaultdict, deque
  from itertools import chain, combinations, islice, tee
  from pprint import pprint
  from urllib.request import HTTPPasswordMgrWithDefaultRealm, ProxyBasicAuthHandler, ProxyDigestAuthHandler, ProxyHandler, build_opener, getproxies, install_opener
  from nltk.collections import *
  from nltk.internals import deprecated, raise_unorderable_types, slice_bounds
label_desc: Use image node_id 27 for calling a global function with example usage: pad_sequence(sequence, n, pad_left, pad_right, left_pad_symbol, right_pad_symbol) and returns: sequence