Generator expression without parenthesis does not raise SyntaxError

Feature

In CPython, generator expression without parenthesis raises following error

>>> foo(x, z for z in range(10), t, w)
  File "<stdin>", line 1
    foo(x, z for z in range(10), t, w)
           ^^^^^^^^^^^^^^^^^^^^
SyntaxError: Generator expression must be parenthesized

However, In RustPython, it does not matter

>>>>> foo(x, z for z in range(10), t, w)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'foo' is not defined

Python Documentation

首先复现 issue 中的两个生成器表达式示例，并跟踪它们在 RustPython Parser 项目中的处理过程。完成的标准是：带有额外参数且未加括号的生成器表达式会引发文档所述的 SyntaxError，同时有效的生成器表达式仍能继续被正确解析。