def _path_completer_grammar(self) -> _CompiledGrammar:
        """
        Return the grammar for matching paths inside strings inside Python
        code.
        """
        # We make this lazy, because it delays startup time a little bit.
        # This way, the grammar is build during the first completion.
        if self._path_completer_grammar_cache is None:
            self._path_completer_grammar_cache = self._create_path_completer_grammar()
        return self._path_completer_grammar_cache

        Return the grammar for matching paths inside strings inside Python
        code.
        
src/ptpython/completer.py