How to use the astor.op_util.Precedence function in astor

def visit_Num(self, node,
                  # constants
                  new=sys.version_info >= (3, 0)):
        with self.delimit(node) as delimiters:
            self._handle_numeric_constant(node.n)

            # We can leave the delimiters handling in visit_Num
            # since this is meant to handle a Python 2.x specific
            # issue and ast.Constant exists only in 3.6+

            # The Python 2.x compiler merges a unary minus
            # with a number.  This is a premature optimization
            # that we deal with here...
            if not new and delimiters.discard:
                if not isinstance(node.n, complex) and node.n < 0:
                    pow_lhs = Precedence.Pow + 1
                    delimiters.discard = delimiters.pp != pow_lhs
                else:
                    op = self.get__p_op(node)
                    delimiters.discard = not isinstance(op, ast.USub)

def _handle_string_constant(self, node, value, is_joined=False):
        # embedded is used to control when we might want
        # to use a triple-quoted string.  We determine
        # if we are in an assignment and/or in an expression
        precedence = self.get__pp(node)
        embedded = ((precedence > Precedence.Expr) +
                    (precedence >= Precedence.Assign))

        # Flush any pending newlines, because we're about
        # to severely abuse the result list.
        self.write('')
        result = self.result

        # Calculate the string representing the line
        # we are working on, up to but not including
        # the string we are adding.

        res_index, str_index = self.colinfo
        current_line = self.result[res_index:]
        if str_index:
            current_line[0] = current_line[0][str_index:]
        current_line = ''.join(current_line)

def __getattr__(self, name, defaults=dict(keywords=(),
                    _pp=Precedence.highest).get):
        """ Get an attribute of the node.
            like dict.get (returns None if doesn't exist)
        """
        if not name.startswith('get_'):
            raise AttributeError
        geta = getattr
        shortname = name[4:]
        default = defaults(shortname)

        def getter(node):
            return geta(node, shortname, default)

        setattr(self, name, getter)
        return getter

def _handle_string_constant(self, node, value, is_joined=False):
        # embedded is used to control when we might want
        # to use a triple-quoted string.  We determine
        # if we are in an assignment and/or in an expression
        precedence = self.get__pp(node)
        embedded = ((precedence > Precedence.Expr) +
                    (precedence >= Precedence.Assign))

        # Flush any pending newlines, because we're about
        # to severely abuse the result list.
        self.write('')
        result = self.result

        # Calculate the string representing the line
        # we are working on, up to but not including
        # the string we are adding.

        res_index, str_index = self.colinfo
        current_line = self.result[res_index:]
        if str_index:
            current_line[0] = current_line[0][str_index:]
        current_line = ''.join(current_line)

def loop_args(args, defaults):
            set_precedence(Precedence.Comma, defaults)
            padding = [None] * (len(args) - len(defaults))
            for arg, default in zip(args, padding + defaults):
                self.write(write_comma, arg)
                self.conditional_write('=', default)