7.2.5 Variable number of arguments

Lists and dictionaries may be used to define or call functions with a variable number of arguments. Let's define a list and a dictionary as follows:

data = [[1,2],[3,4]]    
style = dict({'linewidth':3,'marker':'o','color':'green'})

Then we can call the plot function using starred (*) arguments:

plot(*data,**style)

A variable name prefixed by *, such as *data in the preceding example, means that a list that gets unpacked to provide the function with its arguments. In this way, a list generates positional arguments. Similarly, a variable name prefixed by **, such as **style in the example, unpacks a dictionary to keyword arguments; see Figure 7.1:

Figure 7.1: Starred arguments in function calls

You might also want to use the reverse process, where all given positional arguments are packed into a list and all keyword arguments are packed into a dictionary when passed to a function. In the function...