anchor.diff:  Quoted and Balanced strings starting with `%` might have an optional
   alphabetic *expansion type* between the `%` and their delimiter (which
   is always a punctuation character). This *expansion type* defines how the
  -string content is going to be expanded.
  +string content is going to be expanded. Rules for expanding and escaping typed
  +expansions are the same as for `%`-strings.
   
   - If the *expansion type* is empty, the string content is used verbatim.
   
  
positive.code: 
  === Balanced Strings Examples
  
  - `%{foo}` contents is *foo*
  
  - `%{foo\{bar}}` contents is *foo\{bar}*
  
  == Non Quoted words
  
  
negative.code: punctuation character it is parsed as a quoted string whose delimiter is,
  respectively, `'`, `"` or `X`.
  
  A quoted string contains every character (including whitespaces) until
  its closing delimiter. If its closing delimiter is doubled, then it is
  considered to be part of the string content as a single delimiter.
  
  Inside double quotes, `%`-strings are processed unless the `%` is escaped by
  doubling it. Double quotes inside these nested strings must still be escaped.
  
  No other escaping takes place in quoted strings.
  
  === Quoted Strings Examples
  
  - `'foo'` contains *foo*
  
  - `foo'bar'` is read verbatim, so it contains *foo'bar'*
  
  - `foo%|bar|` is read verbatim, so it contains *foo%|bar|*.
  
  - `'foo''bar'` is a single word whose content is *foo'bar*
  
  - `"baz"""` is a single word whose content is *baz"*.
  
  - `%|foo||bar|` is a single word whose content is *foo|bar*.
  
  - `"foo %|""bar| %%,baz,"` is a single word whose content is *foo "bar %,baz,*.
  
  == Balanced Strings
  
  