How to use the pycparserext.ext_c_parser.FuncDeclExt function in pycparserext

nstr = n.declname if n.declname else ''
            # Resolve modifiers.
            # Wrap in parens to distinguish pointer to array and pointer to
            # function syntax.
            #
            for i, modifier in enumerate(modifiers):
                if isinstance(modifier, c_ast.ArrayDecl):
                    if (i != 0 and isinstance(modifiers[i - 1], c_ast.PtrDecl)):
                        nstr = '(' + nstr + ')'
                    nstr += '[' + self.visit(modifier.dim) + ']'
                elif isinstance(modifier, c_ast.FuncDecl):
                    if (i != 0 and isinstance(modifiers[i - 1], c_ast.PtrDecl)):
                        nstr = '(' + nstr + ')'
                    nstr += '(' + self.visit(modifier.args) + ')'
                elif isinstance(modifier, FuncDeclExt):
                    if (i != 0 and isinstance(modifiers[i - 1], c_ast.PtrDecl)):
                        nstr = '(' + nstr + ')'
                    nstr += '(' + self.visit(modifier.args) + ')'

                    if modifier.asm is not None:
                        nstr += " " + self.visit(modifier.asm)

                    if modifier.attributes.exprs:
                        nstr += (
                                ' __attribute__(('
                                + self.visit(modifier.attributes)
                                + '))')

                elif isinstance(modifier, c_ast.PtrDecl):
                    # BUG FIX: pycparser ignores quals
                    quals = ' '.join(modifier.quals)

quals = quals + ' '
                    nstr = '*' + quals + nstr

            if hasattr(n, "attributes") and n.attributes.exprs:
                nstr += ' __attribute__((' + self.visit(n.attributes) + '))'

            if nstr:
                s += ' ' + nstr
            return s
        elif typ == c_ast.Decl:
            return self._generate_decl(n.type)
        elif typ == c_ast.Typename:
            return self._generate_type(n.type)
        elif typ == c_ast.IdentifierType:
            return ' '.join(n.names) + ' '
        elif typ in (c_ast.ArrayDecl, c_ast.PtrDecl, c_ast.FuncDecl, FuncDeclExt):
            return self._generate_type(n.type, modifiers + [n])
        else:
            return self.visit(n)

elif isinstance(typedecl, c_ast.PtrDecl):
        res.extend(typedecl.quals)
        res.extend(render_type(typedecl.type))
        res.append('*')

    elif isinstance(typedecl, c_ast.IdentifierType):
        res.extend(typedecl.names)

    elif isinstance(typedecl, c_ast.Struct):
        res.extend(['struct', typedecl.name])

    elif isinstance(typedecl, c_ast.Union):
        res.extend(['union', typedecl.name])

    elif isinstance(typedecl, (c_ast.FuncDecl, ext_c_parser.FuncDeclExt)):
        ret = render_type(typedecl.type)
        args = []
        for param in typedecl.args.params:
            args.append(' '.join(render_type(param)))
        ret.append('({})'.format(', '.join(args)))

        res.extend(ret)

    elif isinstance(typedecl, c_ast.ArrayDecl):
        res.extend(render_type(typedecl.type))
        if typedecl.dim is None:
            res.append('[]')
        elif isinstance(typedecl.dim, c_ast.Constant):
            res.append('[{}]'.format(typedecl.dim.value))
        else:
            die('non-constant dimension in array declaration')

def p_direct_abstract_declarator_6(self, p):
        """ direct_abstract_declarator  : direct_abstract_declarator \
                LPAREN parameter_type_list_opt RPAREN asm_opt attributes_opt
        """
        func = FuncDeclExt(
            args=p[3],
            type=None,
            attributes=p[6],
            asm=p[5],
            coord=p[1].coord)

        p[0] = self._type_modify_decl(decl=p[1], modifier=func)

def p_direct_xxx_declarator_6(self, p):
        """ direct_xxx_declarator   : direct_xxx_declarator LPAREN parameter_type_list \
                                            RPAREN asm_opt attributes_opt
                                    | direct_xxx_declarator \
                                            LPAREN identifier_list_opt RPAREN \
                                            asm_opt attributes_opt
        """
        func = FuncDeclExt(
            args=p[3],
            type=None,
            attributes=p[6],
            asm=p[5],
            coord=p[1].coord)

        p[0] = self._type_modify_decl(decl=p[1], modifier=func)