content: import gzip
  import html
  import os
  from functools import lru_cache
  
  import ftfy
  import regex as re
  
  
  @lru_cache()
  def default_bpe():
      return os.path.join(os.path.dirname(os.path.abspath(__file__)), "bpe_simple_vocab_16e6.txt.gz")
  # @lru_cache()
  # def default_bpe():
  #     return "bpe_simple_vocab_16e6.txt.gz"
  
  
  @lru_cache()
  def bytes_to_unicode():
      """
      Returns list of utf-8 byte and a corresponding list of unicode strings.
      The reversible bpe codes work on unicode strings.
      This means you need a large # of unicode characters in your vocab if you want to avoid UNKs.
      When you're at something like a 10B token dataset you end up needing around 5K for decent coverage.
      This is a signficant percentage of your normal, say, 32K bpe vocab.
      To avoid that, we want lookup tables between utf-8 bytes and unicode strings.
      And avoids mapping to whitespace/control characters the bpe code barfs on.
      """
      bs = list(range(ord("!"), ord("~")+1))+list(range(ord("¡"), ord("¬")+1))+list(range(ord("®"), ord("ÿ")+1))
      cs = bs[:]
      n = 0
      for b in range(2**8):
          if b not in bs:
              bs.append(b)
              cs.append(2**8+n)
              n += 1
      cs = [chr(n) for n in cs]
      return dict(zip(bs, cs))
  
  
  def get_pairs(word):
      """Return set of symbol pairs in a word.
      Word is represented as tuple of symbols (symbols being variable-length strings).
      """
      pairs = set()
      prev_char = word[0]
      for char in word[1:]:
          pairs.add((prev_char, char))
          prev_char = char
      return pairs
  
  
  def basic_clean(text):
      text = ftfy.fix_text(text)
      text = html.unescape(html.unescape(text))
      return text.strip()
  
  
  def whitespace_clean(text):
      text = re.sub(r'\s+', ' ', text)
      text = text.strip()
      return text
  
  
  class SimpleTokenizer(object):
      def __init__(self, bpe_path: str = default_bpe()):
          self.byte_encoder = bytes_to_unicode()
          self.byte_decoder = {v: k for k, v in self.byte_encoder.items()}
          merges = gzip.open(bpe_path).read().decode("utf-8").split('\n')
          merges = merges[1:49152-256-2+1]
          merges = [tuple(merge.split()) for merge in merges]
          vocab = list(bytes_to_unicode().values())
          vocab = vocab + [v+'</w>' for v in vocab]
          for merge in merges:
              vocab.append(''.join(merge))
          vocab.extend(['<|startoftext|>', '<|endoftext|>'])
          self.encoder = dict(zip(vocab, range(len(vocab))))
          self.decoder = {v: k for k, v in self.encoder.items()}
          self.bpe_ranks = dict(zip(merges, range(len(merges))))
          self.cache = {'<|startoftext|>': '<|startoftext|>', '<|endoftext|>': '<|endoftext|>'}
          self.pat = re.compile(r"""<\|startoftext\|>|<\|endoftext\|>|'s|'t|'re|'ve|'m|'ll|'d|[\p{L}]+|[\p{N}]|[^\s\p{L}\p{N}]+""", re.IGNORECASE)
  
      def bpe(self, token):
          if token in self.cache:
              return self.cache[token]
          word = tuple(token[:-1]) + ( token[-1] + '</w>',)
          pairs = get_pairs(word)
  
          if not pairs:
              return token+'</w>'
  
          while True:
              bigram = min(pairs, key = lambda pair: self.bpe_ranks.get(pair, float('inf')))
              if bigram not in self.bpe_ranks:
                  break
              first, second = bigram
              new_word = []
              i = 0
              while i < len(word):
                  try:
                      j = word.index(first, i)
                      new_word.extend(word[i:j])
                      i = j
                  except:
                      new_word.extend(word[i:])
                      break
  
                  if word[i] == first and i < len(word)-1 and word[i+1] == second:
                      new_word.append(first+second)
                      i += 2
                  else:
                      new_word.append(word[i])
                      i += 1
              new_word = tuple(new_word)
              word = new_word
              if len(word) == 1:
                  break
              else:
                  pairs = get_pairs(word)
          word = ' '.join(word)
          self.cache[token] = word
          return word
  
      def encode(self, text):
          bpe_tokens = []
          text = whitespace_clean(basic_clean(text)).lower()
          for token in re.findall(self.pat, text):
              token = ''.join(self.byte_encoder[b] for b in token.encode('utf-8'))
              bpe_tokens.extend(self.encoder[bpe_token] for bpe_token in self.bpe(token).split(' '))
          return bpe_tokens
  
      def decode(self, tokens):
          text = ''.join([self.decoder[token] for token in tokens])
          text = bytearray([self.byte_decoder[c] for c in text]).decode('utf-8', errors="replace").replace('</w>', ' ')
          return text
  