Python 3 - Second Edition

17.8    Positional-Only Parameters

In addition to keyword-only parameters, you can also mark positional-only parameters. This refers to function parameters that may only be passed as a positional argument and not as a keyword argument.

Positional-only parameters must be placed at the very beginning of the parameter list of a function and are separated from the remaining parameters by a forward slash (/):

>>> def f(a, b, /, c, d):...     print(a, b, c, d)...>>> f(1, b=2, c=3, d=4)Traceback (most recent call last):  File "<python-input-1>", line 1, in <module>    f(1, b=2, c=3, d=4)    ~^^^^^^^^^^^^^^^^^^TypeError: f() got some positional-only arguments passed as keyword arguments: 'b'>>> f(1, 2, c=3, d=4)1 2 3 4  

The syntax for defining positional-only ...