anchor.diff:      +item
           |  A function #[code infixes_finditer], to handle non-whitespace
           |  separators, such as hyphens etc.
  +
  +    +item
  +        |  (Optional) A boolean function #[code token_match] matching strings
  +        |  that should never be split, overriding the previous rules.
  +        |  Useful for things like URLs or numbers.
   
   p
       |  You shouldn't usually need to create a #[code Tokenizer] subclass.
  
positive.code: 
  p
      |  Let's imagine you wanted to create a tokenizer for a new language. There
      |  are four things you would need to define:
  
  +list("numbers")
      +item
  
negative.code:     |  algorithm in Python, optimized for readability rather than performance:
  
  +code.
      def tokenizer_pseudo_code(text, special_cases,
                                find_prefix, find_suffix, find_infixes):
          tokens = []
          for substring in text.split(' '):
              suffixes = []
  