Suggested by @MostAwesomeDude in [this](https://github.com/satwikkansal/wtfPython/issues/1) issue.

**Output:**

>>> def f(x, y,):

... print(x, y)

>>> def g(x=4, y=5,):

... print(x, y)

>>> def h(x, **kwargs,):

File "<stdin>", line 1

def h(x, **kwargs,):

^

SyntaxError: invalid syntax

>>> def h(*args,):

File "<stdin>", line 1

def h(*args,):

^

SyntaxError: invalid syntax

- Trailing comma is not always legal in formal parameters list of a Python function.

- In Python, the argument list is defined partially with leading commas and partially with trailing commas. This conflict causes situations where a comma is trapped in the middle, and no rule accepts it.

- **Note:** The trailing comma problem is [fixed in Python 3.6](https://bugs.python.org/issue9232). The remarks in [this](https://bugs.python.org/issue9232#msg248399) post discuss in brief different usages of trailing commas in Python.