docs: def _error_if_symbol_unused(symbol_word,
                              technical_words_dictionary,
                              line_offset,
                              col_offset):
      """Return SpellcheckError if this symbol is not used in the code."""
      result = technical_words_dictionary.corrections(symbol_word,
                                                      distance=5,
                                                      prefix=0)
      if not result.valid:
          return SpellcheckError(symbol_word,
                                 line_offset,
                                 col_offset,
                                 result.suggestions,
                                 SpellcheckError.TechnicalWord)