3.5 Defining position-only parameters with the / separator
We can use the / character in the parameter list to separate the parameters into two groups. Before /, all argument values work positionally. After the / parameter, argument values may be given positionally, or names may be used.
This should be used for functions where the following conditions are all true:
A few positional parameters are used (no more than three).
And they are all required.
And the order is so obvious that any change might be confusing.
This has always been a feature of the standard library. As an example, the math.sin() function can only use positional parameters. The formal definition is as follows:
>>> help(math.sin)
Help on built-in function sin in module math:
sin(x, /)
Return the sine of x (measured in radians).Even though...
