Python Language Tutorial => *args and **kwargs

Remarks

There a few things to note:

The names args and kwargs are used by convention, they are not a part of the language specification. Thus, these are equivalent:
```
 def func(*args, **kwargs):
     print(args)
     print(kwargs)
```
```
 def func(*a, **b):
     print(a)
     print(b)
```

You may not have more than one args or more than one kwargs parameters (however they are not required)

 def func(*args1, *args2):
 #   File "<stdin>", line 1
 #     def test(*args1, *args2):
 #                      ^
 # SyntaxError: invalid syntax

 def test(**kwargs1, **kwargs2):
 #   File "<stdin>", line 1
 #     def test(**kwargs1, **kwargs2):
 #                       ^
 # SyntaxError: invalid syntax

If any positional argument follow *args, they are keyword-only arguments that can only be passed by name. A single star may be used instead of *args to force values to be keyword arguments without providing a variadic parameter list. Keyword-only parameter lists are only available in Python 3.
```
 def func(a, b, *args, x, y):
     print(a, b, args, x, y)

 func(1, 2, 3, 4, x=5, y=6)
 #>>> 1, 2, (3, 4), 5, 6
```
```
 def func(a, b, *, x, y):
     print(a, b, x, y)

 func(1, 2, x=5, y=6)
 #>>> 1, 2, 5, 6
```

**kwargs must come last in the parameter list.

 def test(**kwargs, *args):
 #   File "<stdin>", line 1
 #     def test(**kwargs, *args):
 #                      ^
 # SyntaxError: invalid syntax

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