code: def process_docstring(app, what, name, obj, options, lines):
      
      result = [re.sub(r'U\{([^}]*)\}', r'\1',
                       re.sub(r'(L|C)\{([^}]*)\}', r':py:obj:`\2`',
                              re.sub(r'@(' + '|'.join(FIELDS) + r')', r':\1',
                                     l)))
                for l in lines]
      lines[:] = result[:]
docs: Process the docstring for a given python object.
      Note that the list 'lines' is changed in this function. Sphinx
      uses the altered content of the list.