e consist of three
parts separated by <code>sep</code>.
The first part is the argument name, if it exists, else the function.
The second part is the name of the variable being summarised if <code>long_names == TRUE</code> and
the first part is the function name, else ""
The third part is the names of the object returned by the summarizing function, if they
exist, else a sequence of consecutive integers or "" if there is only one component
returned by the summarizing function.
See the examples.</p>
    </div